Remove MessageCompiler.annotation (#634)

Author: AdrienVannson

src/betterproto/plugin/models.py

@@ -328,12 +328,6 @@ def proto_name(self) -> str:
     def py_name(self) -> str:
         return pythonize_class_name(self.proto_name)
 
-    @property
-    def annotation(self) -> str:
-        if self.repeated:
-            return self.typing_compiler.list(self.py_name)
-        return self.py_name
-
     @property
     def deprecated_fields(self) -> Iterator[str]:
         for f in self.fields: