change git icon

### Description
Hi,

I find the current git icon not so fitting in with the rest of the icons (since it is simple the word "git"). It is probably not so helpful when going through files and folders to find something like this (especially the "git .git" combo)

I would propose to use the alternative git icons instead:

I will shortly post a pull request for it.
- Relevant Issues : (none)
- Relevant PRs : (none)
- Type of issue :
- [ ] Installation
- [ ] Font-related
- [x] Feature request
- [ ] Bug in existing feature
- [ ] Developer mode : Code quality / Tests / Documentation

The issue names no file, test, or entry point. Locate the current git icon mapping in the colorls repository, compare it with the proposed alternative, and verify the new icon appears for git-related entries without changing other icons.

Written by the indexing model from the issue text.