ci: fix permissions

Author: szkiba

.github/workflows/release.yml

@@ -10,6 +10,8 @@ jobs:
   release:
     name: Release
     uses: grafana/xk6/.github/workflows/extension-release.yml@v0.19.2
+    permissions:
+      contents: write
     with:
       cgo: true
       go-version: ${{vars.GO_VERSION}}