l10n: bg.po: Updated Bulgarian translation (5856t)

[alshopov]

Thanks for taking the time to contribute to Git! Please be advised that the
Git community does not use github.com for their contributions. Instead, we use
a mailing list ([email protected]) for code submissions, code reviews, and
bug reports. Nevertheless, you can use GitGitGadget (https://gitgitgadget.github.io/)
to conveniently send your Pull Requests commits to our mailing list.

For a single-commit pull request, please leave the pull request description
empty: your commit message itself should describe your changes.

Please read the "guidelines for contributing" linked above!

[github-actions]

Warnings found by git-po-helper in workflow #1017:

------------------------------------------------------------------------------
INFO [po/bg.po@3a8e21c]	5857 translated messages. 
------------------------------------------------------------------------------
WARNING [po/bg.po@3a8e21c]	mismatched patterns: git pack-objects 
WARNING [po/bg.po@3a8e21c]	>> msgid: Could not spawn pack-objects 
WARNING [po/bg.po@3a8e21c]	>> msgstr: Командата „git pack-objects“ не може да се стартира 
WARNING [po/bg.po@3a8e21c]                           
INFO checking commits: 1 passed.                  
------------------------------------------------------------------------------
INFO downloading pot file from https://github.com/git-l10n/pot-changes/raw/pot/master/po/git.pot 

[jiangxin]

Thanks for the prompt response, @alshopov. I'll merge this by Sunday.