Git Submodules changelog links may 404 with a `.git` suffix

[jamietanna]

As noted in #41332, the automagic changelog link on PRs introduced (off the back of additional changes in #40472) may lead to 404s

For instance Lombiq/Open-Source-Orchard-Core-Extensions#1239 is raised for:

          {
            "currentDigest": "fcbbcfcdeec19b28bbdd8ecabdc329575027b518",
            "currentValue": "dev",
            "depName": "tools/Lombiq.GitHub.Actions",
            "packageName": "https://github.com/Lombiq/GitHub-Actions.git",
            "sourceUrl": "https://github.com/Lombiq/GitHub-Actions.git",
            "versioning": "git",
            "warnings": [],
            "updates": [
              {
                "updateType": "digest",
                "newValue": "dev",
                "newDigest": "005e08c9deec7d854c8ddfb07ac5f9ebcfd584bb",
                "branchName": "renovate/all-dependencies"
              }
            ]
          },

The correct link is:

-https://redirect.github.com/Lombiq/GitHub-Actions.git/compare/fcbbcfcdeec19b28bbdd8ecabdc329575027b518..005e08c9deec7d854c8ddfb07ac5f9ebcfd584bb
+https://redirect.github.com/Lombiq/GitHub-Actions/compare/fcbbcfcdeec19b28bbdd8ecabdc329575027b518..005e08c9deec7d854c8ddfb07ac5f9ebcfd584bb

It might be possible to strip the .git, at least when we're on GitHub, but doing it across all Platforms may be risky.