Compatibility with PostgreSQL v12+

Currently, the queryparser seems to miss some functions from PostgreSQL v12+. 
As an example, the following test fails
```yml
  - SELECT log10(mvir) from mdr1.bdmv 
    WHERE snapnum=85
  - ['mdr1.bdmv.mvir', 'mdr1.bdmv.snapnum']
  - ['where']
  -
  -
  -
```
log10() was introduced with PostgreSQL 12. 