fix(ci): self-heal module cache on verify failure

.gitea/workflows/prepare-release.yml

@@ -45,8 +45,15 @@ jobs:
       - name: Module hygiene
         run: |
           set -euo pipefail
+
           go mod tidy
-          go mod verify
+
+          if ! go mod verify; then
+            echo "go mod verify failed; refreshing module cache and retrying" >&2
+            go clean -modcache
+            go mod download
+            go mod verify
+          fi
 
       - name: Restore cached gosec binary
         id: cache-gosec