Update Github CI versions.

- Use latest macOS and default Xcode versions for primary CI environment.
- Github CI no longer supports macOS 11.
  Update legacy CI to macOS 12 and Xcode 13.4.1.

.github/workflows/CI.yml

@@ -15,17 +15,17 @@ jobs:
  build:
  strategy:
  matrix:
- xcode: [ "15.0" ]
+ # Primary build on latest macOS and its default Xcode version
+ os: [ "macos-latest" ]
  platform: [ "all", "macos", "ios" ]
- os: [ "macos-13" ]
  upload_artifacts: [ true ]
 
- # Legacy configurations
+ # Legacy build. Up to 3 versions behind latest (or beta).
  include:
- - xcode: "12.5.1"
-  platform: "macos"
-  os: "macos-11"
-  upload_artifacts: false
+ os: "macos-12"
+ xcode: "13.4.1"
+ platform: "macos"
+ upload_artifacts: false
  fail-fast: false
 
  name: 'MoltenVK (Xcode ${{ matrix.xcode }} - ${{ matrix.platform }})'