handle git commit tags

[jdkandersson]

This PR adds support for retrieving content from a tag that is directly attached to a git commit. It would be good to change the e2e tests as well, I propose this to be done in a follow up PR as I think using git by default creates direct tags rather than indirect tags

[github-actions[bot]]

Test coverage for b6ed8ec98a3a5b00efc30d996a46bc4f3eef7142

Name                      Stmts   Miss Branch BrPart  Cover   Missing
---------------------------------------------------------------------
src/__init__.py              54      0     10      0   100%
src/action.py               156      0     46      0   100%
src/check.py                 29      0     10      0   100%
src/constants.py              4      0      0      0   100%
src/content.py               52      0      8      0   100%
src/discourse.py            156      0     34      0   100%
src/docs_directory.py        29      0      8      0   100%
src/exceptions.py            14      0      0      0   100%
src/index.py                 28      0      6      0   100%
src/metadata.py              28      0     12      0   100%
src/migration.py            106      0     35      0   100%
src/navigation_table.py      53      0     16      0   100%
src/pull_request.py          17      0      4      0   100%
src/reconcile.py             84      0     40      0   100%
src/repository.py           110      0     24      0   100%
src/types_.py               131      0     22      0   100%
---------------------------------------------------------------------
TOTAL                      1051      0    275      0   100%

Static code analysis report

Run started:2023-04-14 07:12:11.753686

Test results:
    No issues identified.

Code scanned:
    Total lines of code: 9690
    Total lines skipped (#nosec): 14
    Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
    Total issues (by severity):
        Undefined: 0
        Low: 0
        Medium: 0
        High: 0
    Total issues (by confidence):
        Undefined: 0
        Low: 0
        Medium: 0
        High: 0
Files skipped (0):

[jdkandersson]

Feel free to merge if approved, I'll be away until Tuesday next week