Update CI matrix in cmake.yml to remove platforms

Removed Windows and macOS configurations from the CI matrix.

.github/workflows/cmake.yml

@@ -10,21 +10,11 @@ jobs:
       fail-fast: false
       matrix:
         config:
-        - {
-            name: "Windows Latest MSVC",
-            os: windows-latest,
-            build_type: "Debug", cc: "cl", cxx: "cl"
-          }
         - {
             name: "Ubuntu Latest GCC",
             os: ubuntu-latest,
             build_type: "Debug", cc: "gcc", cxx: "g++"
           }
-        - {
-            name: "macOS Latest Clang",
-            os: macos-latest,
-            build_type: "Debug", cc: "clang", cxx: "clang++"
-          }
 
     steps:
     - uses: actions/checkout@v2