fix: Error w/ multiple files using `bump:git`

Fixes issue #42

This fix exposes an existing defect that the previous git version isn't detached when attaching a new one. For example, `0.0.1-9ae2-s` will become `0.0.1-9ae2-s-f512-b`.

This continues on, so after a few runs w/o a patch, the version becomes `0.0.1-9ae2-s-f512-b-f5ed-d`