Re-enable buf breaking rule (#133)

Author: yiminc

Diff for: Makefile

@@ -72,8 +72,7 @@ buf-lint:
 
 buf-breaking:
 	@printf $(COLOR) "Run buf breaking changes check against master branch..."	
-#	@(cd $(PROTO_ROOT) && buf breaking --against '.git#branch=master')
-# TODO: re-enable it after this change
+	@(cd $(PROTO_ROOT) && buf breaking --against '.git#branch=master')
 
 ##### Clean #####
 clean: