Update release steps to add source distribution

Author: mbohlool

scripts/release.sh

@@ -4,6 +4,7 @@
 # as a shell script later.
 
 echo 'git clean -xdf'
+echo 'python setup.py sdist'
 echo 'python setup.py bdist_wheel --universal'
 echo 'twine upload dist/* -r https://upload.pypi.org/legacy/ -u kubernetes'