* Rework change detection via `git diff`
Previous implementation performed simple diff between two versions. New implementation fetches on demand more commits to have the merge base between two branches. Now it will detect only changes introduced by branch that was pushed, instead of mixing with changes introduced meanwhile on the base branch.
* Do not require user provided `githubToken` input (configure default)
* Remove `edited` from workflow example
Idea of this example was to show setup where CI runs only when particular files are changed. Triggering workflow when name or description of PR is edited is not needed for this use case.
* Remove accidental string interpolation from action.yml
* Fix test workflow filters
* Improve self-test
* Add test case for matching any changed file
* Fix workflow test - step `name` was used instead of `id`
* Extend default pull_request trigger types
* Remove `edited` trigger to avoid executing workflow on non-code changes
