CI: Add GitHub Actions cross-platform build

Author: hcbcomeup

.github/workflows/build.yml

@@ -0,0 +1,17 @@
+name: cppbase-cross-platform-build
+on: [push, pull_request]
+
+jobs:
+  build:
+    name: ${{ matrix.os }} build
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Configure CMake
+        run: cmake -B ${{github.workspace}}/build -DCMAKE_BUILD_TYPE=Release
+      - name: Build
+        run: cmake --build ${{github.workspace}}/build --config Release --parallel 4