Add return type for Docker container start (#11905)

stubs/docker/docker/models/containers.pyi

@@ -47,7 +47,7 @@ class Container(Model):
     def rename(self, name): ...
     def resize(self, height, width): ...
     def restart(self, **kwargs): ...
-    def start(self, **kwargs): ...
+    def start(self, **kwargs) -> None: ...
     def stats(self, **kwargs): ...
     def stop(self, **kwargs) -> None: ...
     def top(self, **kwargs): ...