Is support for python 3.7 needed?

[bl-young]

Current implementation of the recursion and new FlowBy classes uses Literal typing which requires python 3.8.

Is there a need to maintain support for python 3.7? It will stop being supported in June 2023

[catherinebirney]

For the sake of implementing all of Matthew's changes, I recommend dropping 3.7 when we pull in his branch.

[matthewlchambers]

While it would be easy enough to remove the use of Literal typing (since it's only used in the type hints and doesn't actually have any run-time effect), I also don't see a need to maintain support for Python 3.7.

[matthewlchambers]

Note that this relates to #238 . Given the discussion there, I propose we move to requiring python >= 3.8, pandas >= 1.4.

[matthewlchambers]

Marking this as answered (with a decision to require python >= 3.8, pandas >= 1.4) unless any objections are raised.

[catherinebirney]

I'll update the develop branch requirements

[bl-young]

because pandas is so widely used across the packages it might be good to do this on a separate branch so that it can be aligned with a specific release