Add contents write permissions (#4445)

Author: philippthun

.github/workflows/bump_bbs_protos.yml

@@ -9,7 +9,7 @@ jobs:
   update-protos:
     runs-on: ubuntu-latest
     permissions:
-      contents: read
+      contents: write
       pull-requests: write
     steps:
       - uses: hmarr/debug-action@v3