VersionInfo: Mimic github's hash styling

[tresf]

The problem:

• Our installers are versioned with git hashes that are invalid due to a leading g.
• The hashes used do not reference the latest PR commit, but rather a merge commit.

For example, this is what our software may be versioned:

• gb353cf1e7 (taken from lmms-1.3.0-alpha.1.760+pr7693.gb353cf1e7-linux-aarch64.AppImage)

This is the commit hash that it references:

• b353cf1

Or put simpler:

gb353cf1e7
_b353cf1__

This makes it visually more difficult to correlate a build to a commit hash.

This PR simply shortens the hash to match github and snags the commit hash from the merge commit description.

Adjacent tasks:

• A PR should be made to correct the download buttons on https://github.com/LMMS/lmms.io to match.
• ✅ DONE: LMMS/lmms.io@f16ae56

[tresf]

Hmm... Something about VersionInfo.cmake doesn't seem to be adding the commit id that I would expect... Investigating.

Edit: Yeah, it's because PRs use merge-commits. I'm not sure this can be easily avoided.

[tresf]

So this does as described, but the merge commit ends up in the file (whereas the PR commit ends up on the download button). It would be really nice to have these match so that we're not trying to cross reference merge-commits to their respective branch commits.

[tresf]

So this does as described, but the merge commit ends up in the file (whereas the PR commit ends up on the download button). It would be really nice to have these match so that we're not trying to cross reference merge-commits to their respective branch commits.

I believe I found a way to get them to match. 🤞

[tresf]

I believe I found a way to get them to match. 🤞

Nope 😆

[tresf]

Got it! Next I'll test the behavior with a force-commit by squashing everything down. Edit: Works.