Fix isort w.r.t. _ast/_collections_abc/_tracemalloc/_warnings (#6329)

stdlib/@python2/ast.pyi

@@ -4,10 +4,9 @@
 # from _ast below when loaded in an unorthodox way by the Dropbox
 # internal Bazel integration.
 import typing as _typing
-from typing import Any, Iterator
-
 from _ast import *
 from _ast import AST, Module
+from typing import Any, Iterator
 
 def parse(source: str | unicode, filename: str | unicode = ..., mode: str | unicode = ...) -> Module: ...
 def copy_location(new_node: AST, old_node: AST) -> AST: ...

stdlib/@python2/warnings.pyi

@@ -1,9 +1,8 @@
+from _warnings import warn as warn, warn_explicit as warn_explicit
 from types import ModuleType, TracebackType
 from typing import List, TextIO, Type, overload
 from typing_extensions import Literal
 
-from _warnings import warn as warn, warn_explicit as warn_explicit
-
 def showwarning(
     message: Warning | str, category: Type[Warning], filename: str, lineno: int, file: TextIO | None = ..., line: str | None = ...
 ) -> None: ...