Compatibility with PostgreSQL v12+

[kimakan]

Currently, the queryparser seems to miss some functions from PostgreSQL v12+.
As an example, the following test fails

  - SELECT log10(mvir) from mdr1.bdmv 
    WHERE snapnum=85
  - ['mdr1.bdmv.mvir', 'mdr1.bdmv.snapnum']
  - ['where']
  -
  -
  -

log10() was introduced with PostgreSQL 12.