CI: Add trigger for upstream releases

.github/workflows/upstream_release.yml

@@ -0,0 +1,16 @@
+name: Upstream Release
+
+on:
+    repository_dispatch:
+        types: [ new_release ]
+
+jobs:
+    publish_new_release:
+        uses: ./.github/workflows/build_and_publish.yml
+        with:
+            mumble_version: ${{ github.event.client_payload.tag }}
+            docker_version: '0'
+            publish: true
+            update_latest: ${{ github.event.client_payload.is_latest }}
+            platforms: "linux/amd64"
+        secrets: inherit