build: add issues write permission to sizediff job

Signed-off-by: deadprogram <ron@hybridgroup.com>

.github/workflows/sizediff.yml

@@ -12,6 +12,7 @@ jobs:
     runs-on: ubuntu-22.04
     permissions:
       pull-requests: write
+      issues: write
     steps:
       # Prepare, install tools
       - name: Add GOBIN to $PATH