Do not import TypedDict from mypy-extensions, use `typing-extensi…

…ons` (#15494)

All recent versions (declared in `setup.py`) have `TypedDict` there. So,
no need to use `mypy-extensions` here.

(crossref: found while working on
typeddjango/django-stubs#1566)

mypy/build.py

@@ -38,9 +38,7 @@
     Sequence,
     TextIO,
 )
-from typing_extensions import Final, TypeAlias as _TypeAlias
-
-from mypy_extensions import TypedDict
+from typing_extensions import Final, TypeAlias as _TypeAlias, TypedDict
 
 import mypy.semanal_main
 from mypy.checker import TypeChecker
@@ -343,7 +341,9 @@ class CacheMeta(NamedTuple):
 
 
 # Metadata for the fine-grained dependencies file associated with a module.
-FgDepMeta = TypedDict("FgDepMeta", {"path": str, "mtime": int})
+class FgDepMeta(TypedDict):
+    path: str
+    mtime: int
 
 
 def cache_meta_from_dict(meta: dict[str, Any], data_json: str) -> CacheMeta: