Matrix test go versions

.github/workflows/ci.yml

@@ -10,15 +10,19 @@ jobs:
 
   ci:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go: [ '', '1.x' ] # '' uses go.mod, 1.x uses latest go
     steps:
     - uses: actions/checkout@v2
       with:
         path: src/sigs.k8s.io/json/        
 
     - name: Set up Go
-      uses: actions/setup-go@v2
+      uses: actions/setup-go@v3
       with:
-        go-version: "1.x"
+        go-version-file: 'go.mod'
+        go-version: ${{ matrix.go }}
         stable: true
         check-latest: true
 
@@ -45,7 +49,7 @@ jobs:
     if: github.base_ref
     steps:
       - name: Install Go
-        uses: actions/setup-go@v2
+        uses: actions/setup-go@v3
         with:
           go-version: '1.x'
       - name: Add GOBIN to PATH