Update branches-ignore for the validate workflow

Don't exclude code lines, as there is no workflow calling validate for those.

Author: romain-grecourt

.github/workflows/validate.yml

@@ -18,7 +18,7 @@ name: "Validate"
 on:
   pull_request:
   push:
-    branches-ignore: [ 'master', 'helidon-*.x', 'release-*' ]
+    branches-ignore: [ 'release-*' ]
     tags-ignore: [ '**' ]
   workflow_call:
     inputs: