chore(actions): Backport action needs contents write. (#644) (#645)

Accidentally set the contents permission to read so now the backports
cannot be created.

(cherry picked from commit fdbacde)

Co-authored-by: mcottontensor <80377552+mcottontensor@users.noreply.github.com>

Author: github-actions[bot]

.github/workflows/backport.yml

@@ -5,7 +5,7 @@ on:
     types: ["labeled", "closed"]
 
 permissions:
-  contents: read
+  contents: write
   pull-requests: write
 
 jobs: