Explicitly make the current commit be the one against which the git tag is made

[wilfwilson]

Resolves #36.

[wilfwilson]

I just another test release of the Semigroups package on my fork, v7.8.11 from the fake-release branch, at https://github.com/wilfwilson/Semigroups/releases/tag/v7.8.11

I can confirm that the tag was made against the correct commit, so I believe that this PR is correct and ready to be merged.

[stertooy]

LGTM.

Out of curiosity: is there any difference between using github.sha versus github.ref_name ?

[wilfwilson]

From the documentation:

The short ref name of the branch or tag that triggered the workflow run. This value matches the branch or tag name shown on GitHub. For example, feature-branch-1.

For pull requests, the format is <pr_number>/merge.

So for some workflow runs, such as for a job triggered by workflow_dispatch (which includes most/all package releases), I think the value might be empty.

On the other hand, I think github.sha should always have a value, and it seems more 'precise' anyway, so I went for that one 🙂