Add '--message' to git commit syntax highlighting

[Ultimator14]

Description

Git supports adding a message to a commit via git commit --message. Although the man page only mentions -m "mymessage" and --message="mymessage", omitting the = sign also works. However git commit --message "mymessge" gives wrong highlighting (see issue).

Related Issue(s)

Fixes zdharma-continuum/fast-syntax-highlighting#47

Types of changes

• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] Documentation change
• [ ] New feature (non-breaking change which adds functionality)

Checklist:

• [ ] All new and existing tests passed.
• [ ] I have added tests to cover my changes.
• [ ] I have updated the documentation accordingly.