[docker] Add return type for container labels (#16272)

Author: Mohith1612

stubs/docker/docker/models/containers.pyi

@@ -22,7 +22,7 @@ class Container(Model):
     @property
     def image(self) -> Image | None: ...
     @property
-    def labels(self): ...
+    def labels(self) -> dict[str, str]: ...
     @property
     def status(self) -> str: ...
     @property