Automatically create update PR for Github Actions workflows, like actions/checkout or actions/setup-dart.
To avoid update spam, only updates them once a month & groups the updates into one pull request. Simply stops the actions versions from growing old.
There already are some older action versions in use, causing warnings in CI runs like:
"Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20"
Sampo Silvennoinen