Merge duplicate "version command" tests and remove extemporaneous one

[swainn]

Description

I discovered that there were two test_version_command tests testing basically the same thing. This PR merges the functionality and removes the extra one. Having duplicate tests for this is actually detrimental to the contributor tutorial I'm writing, which modifies the version command.

Changes Made to Code:

• Removed unit_tests/test_version_command.py
• Updated unit_tests/test_tethys_cli/test_vesrion_command.py with mocking approach of the other and tweaked a little.
• Adds tests from some recent additions to site_settings.py that had missing lines of coverage.
• Fixed an issue with the log message in the new site_settings.py code that was untested.
• Fixed typos and revise the Pull Request template

Quality Checks

• New code is 100% tested
• Code has been formatted
• Code has been linted
• Docstrings for new methods have been added

[coveralls]

coverage: 100.0% (+0.03%) from 99.973%
when pulling f241f17 on remove-redundant-version-command-test
into e95effb on main.