Improve types of invoke/env.pyi (#7780)

stubs/invoke/invoke/env.pyi

@@ -1,6 +1,6 @@
 from typing import Any
 
 class Environment:
-    data: Any
-    def __init__(self, config, prefix) -> None: ...
-    def load(self): ...
+    data: dict[str, Any]
+    def __init__(self, config: dict[str, Any], prefix: str) -> None: ...
+    def load(self) -> dict[str, Any]: ...