Improve testing for pre-commit hooks

[klmcadams]

Figure out a way to test the pre-commit hooks in the actions.

Currently, the content of the hooks are tested with pytest, but I have to test my hook changes locally by updating the .pre-commit-config.yaml file:

- repo: local
  hooks:
  - id: add-license-headers
    name: "Add License Headers"
    entry: add-license-headers
    language: python
    files: '(src|examples|tests)/.*\.(py)|\.(proto)'
    require_serial: true
    args:
    - --start_year=2023
    exclude: |
        (?x)^(
              tests/test_add_license_headers_files/bad_chars.py |
              tests/test_add_license_headers_files/index_error.scss
         )$

Next steps

• Look at how hooks are tested in the pre-commit repository & do something similar?
• Create dummy repos for each hook that tests all scenarios for add-license-headers and tech-review respectively