run on github changes

.github/workflows/opam.yml

@@ -2,7 +2,9 @@ name: Build with opam
 
 on:
   push:
-    paths: [ '*.opam' ]
+    paths:
+      - '*.opam'
+      - '.github/**'
   workflow_dispatch:
 
 # only run one instance of this action at a time.