Add build action on new tag

Build various platforms if a new tag matching v* is created

.github/workflows/build_release.yaml

@@ -0,0 +1,39 @@
+name: Build Release
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+jobs:
+  buildForAllPlatforms:
+    name: Build for ${{ matrix.targetPlatform }}
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        targetPlatform:
+          - StandaloneWindows64 # Build a Windows 64-bit standalone.
+          - StandaloneLinux64 # Build a Linux 64-bit standalone.
+          - WebGL # WebGL.
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+          lfs: true
+      - uses: actions/cache@v2
+        with:
+          path: Library
+          key: Library-${{ matrix.targetPlatform }}
+          restore-keys: Library-
+      - uses: game-ci/unity-builder@v2
+        env:
+          UNITY_LICENSE: ${{ secrets.UNITY_LICENSE }}
+          UNITY_EMAIL: ${{ secrets.UNITY_EMAIL }}
+          UNITY_PASSWORD: ${{ secrets.UNITY_PASSWORD }}
+        with:
+          targetPlatform: ${{ matrix.targetPlatform }}
+      - uses: actions/upload-artifact@v2
+        with:
+          name: Build-${{ matrix.targetPlatform }}
+          path: build/${{ matrix.targetPlatform }}