Build playground utils docker container only if the relevant files have changed (#98)

* Update docker-utils-release.yaml

* add internal and main.go to path filters

* remove internal and main.go from path filters

Author: teresper-eth

.github/workflows/docker-utils-release.yaml

@@ -7,6 +7,12 @@ on:
   push:
     branches:
       - main
+    paths:
+      - 'cl-proxy/**'
+      - 'mev-boost-relay/**'
+      - 'go.mod'
+      - 'go.sum'
+      - 'Dockerfile'
 
 jobs:
   docker: