Log Message:
py-sphobjinv: updated to 2.3.1.1

2.3.1.1

Tests

* Update test machinery for the shell examples in the README, downstream of
  the conversion to Markdown.

Administrative

* Added formal support for Python 3.12.
* Removed formal support for Python 3.7, which is end-of-life.
* Bump `checkout` and `setup-python` GitHub Actions versions.
* Convert README from reST to Markdown.
* Fix some broken/redirecting docs links.
* Adjust `flake8` configuration to account for some new lint warnings/errors