.github: Bump iyu/actions-milestone from 1.3.0 to 1.4.0

Bumps [iyu/actions-milestone](https://github.com/iyu/actions-milestone) from 1.3.0 to 1.4.0.
- [Release notes](https://github.com/iyu/actions-milestone/releases)
- [Commits](iyu/actions-milestone@e93115c...d3a9649)

---
updated-dependencies:
- dependency-name: iyu/actions-milestone
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/pr-triage.yml

@@ -22,7 +22,7 @@ jobs:
           labeled: dashboard
       - name: Assign milestone based on target brach name
         # https://github.com/marketplace/actions/pull-request-milestone?version=v1.3.0
-        uses: iyu/actions-milestone@e93115c90ff7bcddee71086e9253f1b6a5f4b48a
+        uses: iyu/actions-milestone@d3a96497d18f333d0419641cc3fcfbd02939a2aa
         with:
           configuration-path: .github/milestone.yml
           repo-token: "${{ secrets.GITHUB_TOKEN }}"