Redid how versioning works.

[yuki-was-taken]

(BTW I realised that the pull request templates doesn't work, I'll make a commit to fix it. It's probably because Github only allows for one template?)

After the commit where the version option was added, I realised that it had a few problems:

1. The commit log was flooded with Github Actions commits.
2. The checks randomly fail because of that step of committing sometime.
3. The src/catniplib/global/currentcommit.nim file causes merge conflicts due to the numbers being different.

So this PR changes the system in a few ways:

1. The version is done at compile time, not after pushing.
2. Github Actions will not need to commit the version number.
3. The version is obtained by a one line shell script.
4. src/catniplib/global/currentcommit.nim is added to the .gitignore file in order to not cause any merge conflicts.