fix: add post-install quarantine removal and ignore spec-graph binary

Author: tyeongkim

.gitignore

@@ -2,4 +2,5 @@
 .sisyphus/
 bin/
 dist/
+spec-graph
 .DS_Store

.goreleaser.yaml

@@ -78,4 +78,7 @@ homebrew_casks:
     description: Typed specification graph CLI for managing requirements, decisions, and phases
     binaries:
       - spec-graph
+    hooks:
+      post:
+        install: 'system_command "/usr/bin/xattr", args: ["-dr", "com.apple.quarantine", "#{staged_path}"]'
     commit_msg_template: "Update {{ .ProjectName }} to {{ .Tag }}"