Support for pre-commit

[akhilputhiry]

It would be nice to support pre-commit so that users can automatically generate change logs while making commits. I guess something like this should do,

# .pre-commit-hooks.yaml

-   id: gitchangelog
    name: gitchangelog
    description: "Generate change logs"
    entry: gitchangelog
    language: python
    types: [python]
    args: []
    always_run: true
    pass_filenames: false
    require_serial: false
    additional_dependencies: []