* add support for python-version-file
* Update action.yml
* update to v4, remove python-version default
* python-version overrides python-version-file, like setup-node
* checks '.python-version' by default if nothing else specified
* update tests, update to checkout@v3
* update build
* appease the linter
* remove old test for default python version
* revert readme changes
* update build
This pull-request improves `setup-python` action to add ability to download specific version of Python on flight if it is not available by default.
**Details:**
`setup-python` action will download and install specific Python version from GitHub releases ([actions/python-versions](https://github.com/actions/python-versions/releases)) in case the version is not found in the local cache. All versions of Python available for installation are published in [actions/python-versions](https://github.com/actions/python-versions) repository.
All available versions are listed in the [version-manifest.json](https://github.com/actions/python-versions/blob/master/versions-manifest.json) file.
**Installation time:**
- Ubuntu / macOS: 10-20 seconds
- Windows: ~ 1 minute (mostly related to fact that we use MSI installer for Python on Windows)
Co-authored-by: MaksimZhukov <v-mazhuk@microsoft.com>
Co-authored-by: Konrad Pabjan <konradpabjan@github.com>
Co-authored-by: Brian Cristante <33549821+brcrista@users.noreply.github.com>
