fix(goreleaser): set explicit base branch for PR

Author: zzxwill

.goreleaser.yml

@@ -73,8 +73,7 @@ brews:
       token: "{{ .Env.GH_PAT }}"
       pull_request:
         enabled: true
-        # Optional: you can specify a base branch if it's not the default
-        # base: master
+        base: master
     directory: Formula
     homepage: "https://github.com/agentsdance/agentx"
     description: "CLI tool for managing MCP servers and skills across AI coding agents"