Support python files

[GlenNicholls]

Just noticed this fails when attempting to use a python file that defines the version. It's standard for py packages to define the version in __init__.py::__version__ variable or in an about.py and __init__.py imports it to set the __version__ variable.

You can see my GHA for a tagged release in https://github.com/GlenNicholls/unraid_parity_scripter/blob/main/.github/workflows/tagged-release.yaml , I see the following error:

Run pocket-apps/action-update-version@v1
Setting input and environment variables
Setting up Octokit and context
Fetching repo task history
Getting author and email from release information
👋 Nice to meet you null (null)!
Checking latest tag "v0.3.0" against input regexp
Extracted new version "0.3.0" from "v0.3.0"
Updating files version field
Error: Unsupported file extension "py".
To add it you can simply submit a PR adding a new parser.