👷 reduce load

.github/workflows/macos.yml

@@ -13,10 +13,26 @@ jobs:
     strategy:
       matrix:
         xcode: [12.4, 12.3, 12.2, 12.1.1, 12.1, 12, 11.7, 11.6, 11.5, 11.4.1, 11.3.1, 11.2.1, 10.3]
-        standard: [11, 14, 17, 20]
     env:
       DEVELOPER_DIR: /Applications/Xcode_${{ matrix.xcode }}.app/Contents/Developer
 
+    steps:
+      - uses: actions/checkout@v2
+      - name: cmake
+        run: cmake -S . -B build -D CMAKE_BUILD_TYPE=Debug -DJSON_BuildTests=On -DJSON_FastTests=ON
+      - name: build
+        run: cmake --build build --parallel 10
+      - name: test
+        run: cd build ; ctest -j 10 --output-on-failure
+
+  xcode_standards:
+    runs-on: macos-10.15
+    strategy:
+      matrix:
+        standard: [11, 14, 17, 20]
+    env:
+      DEVELOPER_DIR: /Applications/Xcode_12.4.app/Contents/Developer
+
     steps:
       - uses: actions/checkout@v2
       - name: cmake