fix: Remove python 3.7 due to end of life (EOL)

[chalmerlowe]

Removes support for Python 3.7 due to end of life (EOL)

[chalmerlowe]

@parthea

I seem to recall that there are some other steps in involved (was it something to do with pushing a CL to our internal repo?).

I attempted to create such a CL: cl/610397808, let me know if there is more that needs doing.

Any help you can offer is appreciated.

[parthea]

Also need to remove python 3.7 in sync-repo-settings.yaml for both unit tests and samples

python-bigquery-pandas/.github/sync-repo-settings.yaml

Line 14 in 366cb55

- 'unit (3.7)'

[parthea]

Also update the versions here :

python-bigquery-pandas/samples/snippets/noxfile.py

Line 92 in 366cb55

ALL_VERSIONS = ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]

[parthea]

I just noticed that https://github.com/googleapis/python-bigquery-pandas/blob/main/testing/constraints-3.7.txt could be removed as well (and the contents moved to https://github.com/googleapis/python-bigquery-pandas/blob/main/testing/constraints-3.8.txt).

More information about the constraints files

Pip uses constraints files to add restrictions when resolving dependencies. In our case, we use constraints files to ensure that the lower bound that we advertise is actually checked in a test session. Some libraries also use constraints files to ensure that a wider range of dependency versions are covered across test sessions. Usually, lower bounds are checked in the lowest supported Python version. Constraints files are kept in sync manually with setup.py. If you forget to update the constraints file after updating a dependency's minimum version in setup.py, the test session fails with a constraints error.

[chalmerlowe]

@parthea

Neither of the 3.7 tests is expected or needed to pass.
All other tests have passed.
Can you review and approve?