* Update to norio-nomura/action-swiftlint@3.2.0
* Run swiftlint directly without external action
* Run on macos-latest
* Calculate diff relative to github.base_ref
* Update to actions/checkout@v2
* Checkout with ref to github.head_ref
* Specify bash shell
* Fetch origin master before running git diff
* Checkout with fetch-depth of 0
* Prefix base ref with origin/
* Fetch and find common ancestor manually
* Run SwiftLint against all files
* Lint with --strict
Mattt