Fix unstable channel workflow trigger

Update the branch pattern to 'version-*-dev' to support 3-digit
version branches like 'version-1.54.1-dev'. Also add
'workflow_dispatch' to support manual triggering.

Author: 3405691582

.github/workflows/unstable-channel.yaml

@@ -3,7 +3,8 @@ name: Unstable channel
 on:
   push:
     branches:
-      - 'version-[0-9]+.[0-9]+-dev'
+      - 'version-*-dev'
+  workflow_dispatch:
 
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   contents: read