Enable tag builds for pypi and buildx workflows

.github/workflows/buildx.yml

@@ -4,6 +4,7 @@ on:
   workflow_run:
     workflows: ["tests"]
     branches: [main]
+    tags: [v*]
     types:
       - completed
 

.github/workflows/pypi.yml

@@ -3,6 +3,7 @@ name: pypi
 on:
   push:
     branches: main
+    tags: v*
 
 jobs:
   publish-test: