Trigger builds from labels as well

This is only a workaround for when we want
to generate a new deployment package
without having to push any changes to the deployment
repository too. This was needed due to
github not allowing to re-run old workflows
after some time has passed.

.github/workflows/build_installation_package.yaml

@@ -1,6 +1,9 @@
 name: Build DQMGUI Installation Package
 
-on: [push]
+on:
+  push:
+  label:
+    types: [created]
 
 jobs:
   build_and_upload: