How-to

In your Sphinx conf.py, add the extension:

extensions = [
    "linkify_issues",
]

Then configure the issue URL template:

issue_url_tpl = "https://github.com/git-pull/gp-libs/issues/{issue_id}"

The default issue_re captures the number from text such as #42, and linkify_issues formats issue_url_tpl with that captured issue_id.