ci: add release workflow for automated GitHub releases (#69)

Triggers on version tags (v*.*.*), runs hemtt release, and uploads
the built archive to the corresponding GitHub release.

Author: fank

.github/workflows/release.yml

@@ -0,0 +1,28 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - "v*.*.*"
+
+jobs:
+
+  release:
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: write
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup HEMTT
+        uses: arma-actions/hemtt@v1
+
+      - name: Run HEMTT release
+        run: hemtt release
+
+      - name: Upload release assets
+        uses: softprops/action-gh-release@c95fe1489396fe8a9eb87c0abf8aa5b2ef267fda # v2
+        with:
+          files: .hemttout/release/*.zip