pyln: Adjust the auto-publish task to trigger on tags

I was wondering why the workflow never published, turns out we were triggering on
branch pushes only, not tags. So the branch would get pushed, but the tag is pushed
afterwards, and thus not triggering.

.github/workflows/pypi.yml

@@ -5,6 +5,11 @@ on:
   push:
     branches:
       - master
+    tags:
+      # Semantic versioning tags
+      - 'v[0-9]+.[0-9]+.[0-9]+'
+      # Date style tags
+      - 'v[0-9]{2}.[0-9]{2}'
 jobs:
   deploy:
     name: Build and publish ${{ matrix.package }} 🐍