Updating supported python versions

[teubert]

Updating the supported python versions to drop 3.7 and 3.8 which are no longer actively supported by python (see https://devguide.python.org/versions/). ProgPy development policy is to not support versions once they reach python end-of-life.

This release also adds support for python 3.13 for all but data-driven features. A note is added to the troubleshooting guide for users using python3.13 with datadriven features.

[github-actions]

Thank you for opening this PR. Each PR into dev requires a code review. For the code review, look at the following:

• Reviewer (someone other than author) should look for bugs, efficiency, readability, testing, and coverage in examples (if relevant).
• Ensure that each PR adding a new feature should include a test verifying that feature.
• All errors from static analysis must be resolved.
• Review the test coverage reports (if there is a change) - will be added as comment on PR if there is a change
• Review the software benchmarking results (if there is a change) - will be added as comment on PR
• Any added dependencies are included in requirements.txt, setup.py, and dev_guide.rst (this document)
• All warnings from static analysis must be reviewed and resolved - if deemed appropriate.

[kjjarvis]

This change looks good and satisfies requirements. All tests run except tutorials involving known issue with downloading PCoE dataset.

[lymichelle21]

Looks great! A few nits:

• Would it be helpful to add a last updated date like "as of the time of writing this (April 2025)"?
• Any chance we could capitalize the python3.13 for consistency and change Tensorflow to TensorFlow (realizing I forgot the capitalization in other parts of this file too)?