ci: extend GitHub Actions CI to macOS

- Expand test matrix in GitHub Actions to include macOS alongside Ubuntu
- Add caching for Go build files on macOS runner

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

.github/workflows/go.yml

@@ -29,11 +29,13 @@ jobs:
   test:
     strategy:
       matrix:
-        os: [ubuntu-latest]
+        os: [ubuntu-latest, macos-latest]
         go: [1.18, 1.19, "1.20", 1.21, 1.22]
         include:
           - os: ubuntu-latest
             go-build: ~/.cache/go-build
+          - os: macos-latest
+            go-build: ~/Library/Caches/go-build
     name: ${{ matrix.os }} @ Go ${{ matrix.go }}
     runs-on: ${{ matrix.os }}
     env: