Grant draft-release-notes job contents: write so git push works

Author: trask

.github/workflows/draft-release-notes.yml

@@ -12,6 +12,8 @@ concurrency:
 jobs:
   draft:
     if: github.repository == 'open-telemetry/opentelemetry-java-instrumentation'
+    permissions:
+      contents: write  # for git push to PR branch
     runs-on: ubuntu-latest
     environment: protected
     steps: