Add CI.

.github/workflows/cmake-single-platform.yml

@@ -0,0 +1,28 @@
+name: vtkdiff pipeline
+
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+    branches: [ "master" ]
+
+env:
+  BUILD_TYPE: Release
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Configure CMake
+      run: cmake -B ${{github.workspace}}/build -DCMAKE_BUILD_TYPE=${{env.BUILD_TYPE}}
+    - name: Build
+      run: cmake --build ${{github.workspace}}/build --config ${{env.BUILD_TYPE}}
+    # - name: Test
+    #  working-directory: ${{github.workspace}}/build
+    #  run: ctest -C ${{env.BUILD_TYPE}}
+