PGCompiler not found on later versions of psycopg2

It looks like this is missing on later versions of SQLAlchemy.
I think it is fine to only support SQLAlchemy >= 2.0 - or should we limit the sqlalchemy version first?

oedialect/oedialect/compiler.py

Line 276 in 4b6676d

class OECompiler(postgresql.psycopg2.PGCompiler):

Hey, sorry for the late reply. At the moment this repo is a little out of our current focus. This is mainly because we had to stick to Python 3.6 until recently (the OEP website was running on this version), which prevented us from further updating the sqlalchmey-related code. This problem has finally been solved this week.

I will have a look at the issues here.