add matrix build for different OS

.github/workflows/cmake.yml

@@ -12,7 +12,17 @@ jobs:
     # well on Windows or Mac.  You can convert this to a matrix build if you need
     # cross-platform coverage.
     # See: https://docs.github.com/en/free-pro-team@latest/actions/learn-github-actions/managing-complex-workflows#using-a-build-matrix
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        build: [linux, macos, windows]
+        include:
+          - build: linux
+            os: ubuntu-latest
+          - build: macos
+            os: macos-latest
+          - build: windows
+            os: windows-latest
 
     steps:
     - uses: actions/checkout@v2