Fixes for problems encountered with version determination

[paulromano]

Description

This PR fixes #3318 and fixes #3319. For #3318, I've added an error message telling the user how to resolve the problem. For #3319, I've added a configuration variable that tells RTD to get the full git history so that it can determine the version properly.

Checklist

• I have performed a self-review of my own code
• I have run clang-format (version 15) on any C++ source files (if applicable)
• I have followed the style guidelines for Python source files (if applicable)
• I have made corresponding changes to the documentation (if applicable)
• I have added tests that prove my fix is effective or that my feature works (if applicable)

[shimwell]

I'm seeing version 0.15 in the read the docs build for this PR

https://openmc--3320.org.readthedocs.build/en/3320/

Which is much better than the 0.1 I was seeing before this PR.

I wonder if we also what the last part of the version number which I guess would be something ilke 0.15.1-dev-hash

[paulromano]

Good point @shimwell. I just pushed an update that will show the full version as I don't see any natural reason why it should only show the first time. I think that was just the default that Sphinx gives you unless you configure otherwise.

[shimwell]

Confirmed that read the docs is showing the full version now, nice work

[shimwell]

As this does not change the actual source code and fixes a live issue for a few users I think we can go ahead and merge this straight away.

I have enabled auto-merge.

Feel free to disable if anyone wants to keep this one open fro more time