workflows: add workflow for snap

.github/workflows/build-umu-snap.yml

@@ -0,0 +1,22 @@
+name: UMU Snap Build
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+  release:
+    types: [published]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    name: 🧪 Build snap on amd64
+    runs-on: ubuntu-latest
+    steps:
+      - name: Prepare
+        run: cd umu-launcher/snap
+      - name: 🧪 Build snap on amd64
+        uses: snapcrafters/ci/test-snap-build@main