chore(ci): way to manually trigger the build

Add a way to manually trigger the build without needing to
create a new release, via GitHub action workflow dispatch.

Useful for quickfixes.

.github/workflows/publish.yml

@@ -1,6 +1,7 @@
 name: publish
 
 on:
+  workflow_dispatch:
   push:
     tags:
       - '*'