Upgrade to psycopg 3

[skearnes]

• Use psycopg>=3 instead of psycopg2
• Test on multiple python versions
• Expose rdkit types and rename the table objects to their plural forms

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.27%. Comparing base (4f50b68) to head (523c58c).
Report is 17 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #730      +/-   ##
==========================================
+ Coverage   69.89%   70.27%   +0.38%     
==========================================
  Files          23       23              
  Lines        2368     2345      -23     
  Branches      598      608      +10     
==========================================
- Hits         1655     1648       -7     
+ Misses        599      586      -13     
+ Partials      114      111       -3     

Files	Coverage Δ
ord_schema/message_helpers.py	87.04% <100.00%> (+0.97%)	⬆️

... and 22 files with indirect coverage changes