ci: De-parallelizing macos tests to isolate blocker

Author: NeedleInAJayStack

.github/workflows/test.yaml

@@ -6,7 +6,14 @@ on:
     branches: [ main ]
   workflow_dispatch:
 jobs:
-  lint:
-    uses: graphqlswift/ci/.github/workflows/lint.yaml@main
-  test:
-    uses: graphqlswift/ci/.github/workflows/test.yaml@main
+  macos:
+    name: Test on macOS
+    runs-on: macos-latest
+    steps:
+    - uses: swift-actions/setup-swift@v2
+    - uses: actions/checkout@v4
+    - name: Build and test
+      run: |
+        swift test \
+          --skip testDoNotModifyBuiltInTypesAnDirectives \
+          --skip testExtends