ci(release): upgrade release-please-action to v5

docvet and gepa-adk both cut releases today with fine-grained tokens on v5. This repo was the only one still on v4, whose bundled release-please 17.3.0 returns 403 on release creation with our fine-grained token even though the same token creates releases fine over the REST API.

Author: Alberto-Codes

.github/workflows/release-please.yml

@@ -26,7 +26,7 @@ jobs:
     steps:
       - name: Run release-please
         id: release
-        uses: googleapis/release-please-action@v4
+        uses: googleapis/release-please-action@v5
         with:
           # Use PAT to allow created releases to trigger publish workflow
           # Create PAT with 'repo' scope and add as RELEASE_PLEASE_TOKEN secret