The `tag.gpgSign` config option was added in Git 2.23.0 and seems like
it should be set in addition to `commit.gpgSign` when
`programs.git.signing.signByDefault` is enabled
When setting values using the `git config --set` command, git formats
the file a bit differently. This changes the output so it maps to that
format.
Differences:
* each `key = value` in a section is prefixed by a tab character
* the `=` between the key and the value is surrounded by spaces
PR #1069
