Address issues seen on Heroku

[mmmavis]

To address the two deployment issues seen on Heroku:

1. replace runtime.txt with .python-version
2. add build-requirements.txt for Heroku compatibility

-----> Building on the Heroku-24 stack
-----> Using buildpack: heroku/python
-----> Python app detected
-----> Using Python 3.9.18 specified in runtime.txt
 !     Warning: The runtime.txt file is deprecated.
 !     
 !     The runtime.txt file is deprecated since it has been replaced
 !     by the more widely supported .python-version file:
 !     https://devcenter.heroku.com/changelog-items/3141
 !     
 !     Please delete your runtime.txt file and create a new file named:
 !     .python-version
 !     
 !     Make sure to include the '.' at the start of the filename.
 !     
 !     In the new file, specify your app's Python version without
 !     quotes or a 'python-' prefix. For example:
 !     3.9
 !     
 !     We strongly recommend that you use the major version form
 !     instead of pinning to an exact version, since it will allow
 !     your app to receive Python security updates.
 !     
 !     In the future support for runtime.txt will be removed and
 !     this warning will be made an error.
 !     Warning: Support for Python 3.9 is ending soon!
 !     
 !     Python 3.9 will reach its upstream end-of-life in October 2025,
 !     at which point it will no longer receive security updates:
 !     https://devguide.python.org/versions/#supported-versions
 !     
 !     As such, support for Python 3.9 will be removed from this
 !     buildpack on 7th January 2026.
 !     
 !     Upgrade to a newer Python version as soon as possible, by
 !     changing the version in your runtime.txt file.
 !     
 !     For more information, see:
 !     https://devcenter.heroku.com/articles/python-support#supported-python-versions
 !     Warning: A Python patch update is available!
 !     
 !     Your app is using Python 3.9.18, however, there is a newer
 !     patch release of Python 3.9 available: 3.9.21
 !     
 !     It is important to always use the latest patch version of
 !     Python to keep your app secure.
 !     
 !     Update your runtime.txt file to use the new version.
 !     
 !     We strongly recommend that you do not pin your app to an
 !     exact Python version such as 3.9.18, and instead only specify
 !     the major Python version of 3.9 in your runtime.txt file.
 !     This will allow your app to receive the latest available Python
 !     patch version automatically and prevent this warning.
-----> Discarding cache since:
       - The stack has changed from heroku-20 to heroku-24
       - The Python version has changed from 3.7.8 to 3.9.18
       - The pip version has changed
-----> Installing Python 3.9.18
-----> Installing pip 24.3.1, setuptools 70.3.0 and wheel 0.45.1
-----> Installing SQLite3
-----> Installing dependencies using 'pip install -r requirements.txt'
       Collecting boto3==1.16.26 (from -r requirements.txt (line 7))
         Downloading boto3-1.16.26-py2.py3-none-any.whl.metadata (5.3 kB)
       Collecting botocore==1.19.26 (from -r requirements.txt (line 9))
         Downloading botocore-1.19.26-py2.py3-none-any.whl.metadata (4.7 kB)
       Collecting cachetools==4.1.0 (from -r requirements.txt (line 13))
         Downloading cachetools-4.1.0-py3-none-any.whl.metadata (4.4 kB)
       Collecting certifi==2020.4.5.1 (from -r requirements.txt (line 15))
         Downloading certifi-2020.4.5.1-py2.py3-none-any.whl.metadata (2.7 kB)
       Collecting cffi==1.15.0 (from -r requirements.txt (line 17))
         Downloading cffi-1.15.0-cp39-cp39-manylinux_2_12_x86_64.manylinux2010_x86_64.whl.metadata (1.2 kB)
       Collecting chardet==3.0.4 (from -r requirements.txt (line 19))
         Downloading chardet-3.0.4-py2.py3-none-any.whl.metadata (3.2 kB)
       Collecting cryptography==36.0.1 (from -r requirements.txt (line 21))
         Downloading cryptography-36.0.1-cp36-abi3-manylinux_2_24_x86_64.whl.metadata (5.4 kB)
       Collecting defusedxml==0.6.0 (from -r requirements.txt (line 23))
         Downloading defusedxml-0.6.0-py2.py3-none-any.whl.metadata (31 kB)
       Collecting dj-database-url==0.5.0 (from -r requirements.txt (line 25))
         Downloading dj_database_url-0.5.0-py2.py3-none-any.whl.metadata (2.7 kB)
       Collecting django==2.2.13 (from -r requirements.txt (line 27))
         Downloading Django-2.2.13-py3-none-any.whl.metadata (3.6 kB)
       Collecting django-ajax-selects==1.9.1 (from -r requirements.txt (line 36))
         Downloading django_ajax_selects-1.9.1-py3-none-any.whl.metadata (1.3 kB)
       Collecting django-allauth==0.48.0 (from -r requirements.txt (line 38))
         Downloading django-allauth-0.48.0.tar.gz (658 kB)
         Preparing metadata (setup.py): started
         Preparing metadata (setup.py): finished with status 'error'
         error: subprocess-exited-with-error
         
         × python setup.py egg_info did not run successfully.
         │ exit code: 1
         ╰─> [6 lines of output]
             Traceback (most recent call last):
               File "<string>", line 2, in <module>
               File "<pip-setuptools-caller>", line 34, in <module>
               File "/tmp/pip-install-e2e9g0ox/django-allauth_56f6c2b86b644876bbaa7d1b25dab82b/setup.py", line 9, in <module>
                 from setuptools import convert_path, find_packages, setup
             ImportError: cannot import name 'convert_path' from 'setuptools' (/app/.heroku/python/lib/python3.9/site-packages/setuptools/__init__.py)
             [end of output]
         
         note: This error originates from a subprocess, and is likely not a problem with pip.
       error: metadata-generation-failed
       
       × Encountered error while generating package metadata.
       ╰─> See above for output.
       
       note: This is an issue with the package mentioned above, not pip.
       hint: See above for details.
 !     Error: Unable to install dependencies using pip.
 !     
 !     See the log output above for more information.
 !     Push rejected, failed to compile Python app.
 !     Push failed

[danielfmiranda]

Thanks @mmmavis! LGTM 🙌