ci: add contents:write permission for release job (#803)

GoReleaser needs contents:write to create GitHub releases and
upload assets. Without it, the GITHUB_TOKEN defaults to none
for contents when job-level permissions are specified.

Author: dirien

.github/workflows/ci.yaml

@@ -36,6 +36,7 @@ jobs:
           make test coverage
   release:
     permissions:
+      contents: write
       id-token: write
       packages: write
     needs: build