fix(ci): Permissions (#1771)

Author: sthulb

.github/workflows/release-prep.yml

@@ -14,6 +14,8 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       id-token: write
+      pull-requests: write
+      contents: write
     steps:
       - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9  # v3.5.3
       - name: Get current date
@@ -82,4 +84,4 @@ jobs:
           body: |
             This is automated release prep. Remember to update [CHANGELOG.md](https://github.com/aws-powertools/powertools-lambda-java/blob/prep-release-${{ github.event.inputs.targetRelease }}/CHANGELOG.md) to capture changes in this release. Please review changes carefully before merging.
             
-            * [ ] Updated CHANGELOG.md
+            * [ ] Updated CHANGELOG.md