Fix goreleaser cask conflicts syntax: use object not string

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: nicksenap

go/.goreleaser.yml

@@ -46,4 +46,4 @@ homebrew_casks:
     binaries:
       - gw
     conflicts:
-      - grove
+      - cask: grove