Update peter-evans/create-pull-request action to v7

Author: elastic-renovate-prod[bot]

.github/workflows/serverless-patch.yml

@@ -42,7 +42,7 @@ jobs:
       - name: Apply patch from stack to serverless
         id: apply-patch
         run: $GITHUB_WORKSPACE/stack/.github/workflows/serverless-patch.sh
-      - uses: peter-evans/create-pull-request@c5a7806660adbe173f04e3e038b0ccdcd758773c # v6
+      - uses: peter-evans/create-pull-request@5e914681df9dc83aa4e4905692ca88beb2f9e91f # v7
         with:
           token: ${{ secrets.GH_TOKEN }}
           path: serverless