Sunset support for Python 3.7

[jdw25]

3.7 is Unsupported/End-of-Life since 2023-06-27. See:

• https://devguide.python.org/versions/
• https://peps.python.org/pep-0537/

Also see: https://github.com/move-coop/parsons/issues/932

Note: @KasiaHinkson can advise on TMC needs here.

[jdw25]

relates to Dockerfile: https://github.com/move-coop/parsons/blob/main/Dockerfile Note: This is the only 3.7 dependency for TMC