Add permissions that were missed on the first pass (#2542)

Co-authored-by: otelbot <197425009+otelbot@users.noreply.github.com>

.github/workflows/prepare-release.yml

@@ -11,6 +11,8 @@ permissions:
 
 jobs:
   create-pull-request:
+    permissions:
+      contents: write # required for pushing changes
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2