Add stubs for flake8-simplify (#6480)

stubs/flake8-simplify/METADATA.toml

@@ -0,0 +1 @@
+version = "0.14.*"

stubs/flake8-simplify/flake8_simplify.pyi

@@ -0,0 +1,8 @@
+import ast
+from typing import Any, Generator, Type
+
+class Plugin:
+    name: str
+    version: str
+    def __init__(self, tree: ast.AST) -> None: ...
+    def run(self) -> Generator[tuple[int, int, str, Type[Any]], None, None]: ...