restrict to pandas2.0

[AdamOrmondroyd]

Description

Upgrading to pandas2.1 has introduced a number of issues, so restrict to pandas2.0 in the meantime until #335 is ready.

Fixes #336

Checklist:

• I have performed a self-review of my own code
• My code is PEP8 compliant (flake8 anesthetic tests)
• My code contains compliant docstrings (pydocstyle --convention=numpy anesthetic)
• New and existing unit tests pass locally with my changes (python -m pytest)
• I have added tests that prove my fix is effective or that my feature works
• I have appropriately incremented the semantic version number in both README.rst and anesthetic/_version.py

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (1bddc80) 100.00% compared to head (2fdba20) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #337   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           34        34           
  Lines         2858      2858           
=========================================
  Hits          2858      2858           

Files Changed	Coverage Δ
anesthetic/_version.py	100.00% <100.00%> (ø)

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.