MINOR: Restrict trigger push branch for GitHub Workflow (#1204)

Feature branches rarely need their own CI runs: the code is already
tested when a pull request is opened against a release branch. If the
push trigger has no branch restriction and pull_request is also
configured, every push to a branch with an open PR runs the workflow
twice: once for the push and once for the PR synchronisation.

Always give the push trigger an explicit list of branches: this stops
branches created from a release branch from inheriting its workflow
runs.

see
https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=430408443#GitHubActionsRecommendedPractices-Restrictthepushtriggertospecificbranches

## What's Changed

Please fill in a description of the changes here.

**This contains breaking changes.** <!-- Remove this line if there are
no breaking changes. -->

Closes #NNN.

Note that I needed to recreate a PR as the previous one was closed
#1202 (comment)

Signed-off-by: Aurélien Pupier <apupier@ibm.com>

Author: apupier

.github/workflows/dev.yml

@@ -19,7 +19,9 @@ name: Dev
 
 on:
   pull_request: {}
-  push: {}
+  push:
+    branches-ignore:
+      - dependabot/**
 
 concurrency:
   group: ${{ github.repository }}-${{ github.ref }}-${{ github.workflow }}