CI: Update CARS.md every night

[ugtthis]

Example automated commit: ugtthis@8f0e2c3

---

Note: below comments is the same as the openpilot CI PR

This resolves #1570

• updates 12am PST
• ability to manually trigger
• only commits when there is a change. Line 46
  https://github.com/stefanzweifel/git-auto-commit-action/blob/master/entrypoint.sh

if [ -n "$(git diff --staged)" ] || "$INPUT_SKIP_DIRTY_CHECK"; then
            _local_commit

            _tag_commit

            _push_to_github
        else
            _set_github_output "changes_detected" "false"

            echo "Working tree clean. Nothing to commit.";
        fi

Things to note:

This is using default settings. Let me know if you want these changed git-auto-commit-action

# Optional commit user and author settings
    commit_user_name: My GitHub Actions Bot # defaults to "github-actions[bot]"
    commit_user_email: my-github-actions-bot@example.org # defaults to "41898282+github-actions[bot]@users.noreply.github.com"
    commit_author: Author <actions@github.com> # defaults to "username <username@users.noreply.github.com>", where "username" belongs to the author of the commit that triggered the run