add release to action

.github/workflows/build.yml

@@ -5,3 +5,19 @@ jobs:
     uses: zmkfirmware/zmk/.github/workflows/build-user-config.yml@main
     with: 
       archive_name: "ak3"
+
+  release:
+    runs-on: ubuntu-latest
+    if: startsWith(github.ref, 'refs/tags/')
+    permissions:
+      contents: write  # allow workflow to commit to the repo
+    needs: build
+    steps:
+    - uses: actions/download-artifact@v4
+      with:
+        name: ak3
+        run-id: ${{ github.event.workflow_run.id }}
+    - name: Release
+      uses: softprops/action-gh-release@v2
+      with:
+        files: ak3_*.uf2