Description

The elements in version_files may contain not only a file path, but also a regex after a colon. Thus make sure to only pass the file path to
git add.

Fixes a regression introduced in 12b56ad.

Checklist

• Add test cases to all the changes you introduce
• Run ./scripts/format and ./scripts/test locally to ensure this change passes linter check and test
• Test the changes on the local machine manually
• Update the documentation for the changes

Expected behavior

CHANGELOG.md gets git added and commited no matter what version files (+ regex) one specifies.

Before and After

Before the following, broken, command was executed:
git add CHANGELOG.md pyproject.toml:^version src/my_package/__init__.py:^__version__

With this MR, the command looks like this:
git add CHANGELOG.md pyproject.toml src/my_package/__init__.py

Steps to Test This Pull Request

Have the following commitizen settings in pyproject.toml file:

[tool.commitizen]
version = "1.0.2"
version_files = [
    "pyproject.toml:^version",  # use regex to only update version at start of line (https://github.com/commitizen-tools/commitizen/issues/496)
    "src/my_package/__init__.py:^__version__",
]
tag_format = "v$major.$minor.$patch$prerelease"

In the git repo of my_package make sure there is no CHANGELOG.md file tracked by git yet.
Running cz bump will update the version correctly and also write the changelog file, but fail to git add it.

Additional context