fix: add tag trigger to main.yml workflow

Added missing `tags: ['v*']` trigger to main.yml to enable the
release workflow chain when version tags are pushed.

This aligns with txaio, autobahn-python, zlmdb, cfxdb, and wamp-xbr
which all have this trigger configured.

Also added `workflow_dispatch` for manual triggering.

Note: This work was completed with AI assistance (Claude Code).

Author: oberstet

.github/workflows/main.yml

@@ -4,9 +4,12 @@ on:
   push:
     branches:
       - master
+    tags:
+      - 'v*'  # Trigger on version tags for release workflow chain
   pull_request:
     branches:
       - master
+  workflow_dispatch:
 
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