Fix synced itertools (python#20700)

Fixes python#20697 

Changed the base type of `itertools.batched` from `Iterator[tuple[_T_co,
...]]` to `Iterator[_T_co]` in the stub and patch files so that mypy no
longer reports an error due to a mismatched return type of `__next__`.

Author: p-sawicki

misc/typeshed_patches/0001-Revert-Remove-redundant-inheritances-from-Iterator.patch

@@ -289,7 +289,7 @@ index 8a924ad8b..5c2bf7f83 100644
  if sys.version_info >= (3, 12):
      @disjoint_base
 -    class batched(Generic[_T_co]):
-+    class batched(Iterator[tuple[_T_co, ...]], Generic[_T_co]):
++    class batched(Iterator[_T_co], Generic[_T_co]):
          if sys.version_info >= (3, 13):
              @overload
              def __new__(cls, iterable: Iterable[_T], n: Literal[1], *, strict: Literal[True]) -> batched[tuple[_T]]: ...

mypy/typeshed/stdlib/itertools.pyi

@@ -341,7 +341,7 @@ if sys.version_info >= (3, 10):
 
 if sys.version_info >= (3, 12):
     @disjoint_base
-    class batched(Iterator[tuple[_T_co, ...]], Generic[_T_co]):
+    class batched(Iterator[_T_co], Generic[_T_co]):
         if sys.version_info >= (3, 13):
             @overload
             def __new__(cls, iterable: Iterable[_T], n: Literal[1], *, strict: Literal[True]) -> batched[tuple[_T]]: ...

test-data/unit/check-itertools.test

@@ -0,0 +1,47 @@
+[case testItertoolsBatched312]
+# flags: --python-version 3.12
+
+from itertools import batched
+
+b = batched([0], 1)
+reveal_type(b)  # N: Revealed type is "itertools.batched[builtins.tuple[builtins.int, ...]]"
+reveal_type(b.__next__())  # N: Revealed type is "builtins.tuple[builtins.int, ...]"
+
+reveal_type(batched([0, 0], 2))  # N: Revealed type is "itertools.batched[builtins.tuple[builtins.int, ...]]"
+reveal_type(batched([0, 0, 0], 3))  # N: Revealed type is "itertools.batched[builtins.tuple[builtins.int, ...]]"
+reveal_type(batched([0, 0, 0, 0], 4))  # N: Revealed type is "itertools.batched[builtins.tuple[builtins.int, ...]]"
+reveal_type(batched([0, 0, 0, 0, 0], 5))  # N: Revealed type is "itertools.batched[builtins.tuple[builtins.int, ...]]"
+
+reveal_type(batched([0], 2))  # N: Revealed type is "itertools.batched[builtins.tuple[builtins.int, ...]]"
+reveal_type(batched([0], 2))  # N: Revealed type is "itertools.batched[builtins.tuple[builtins.int, ...]]"
+
+def f() -> int:
+    return 3
+
+reveal_type(batched([0, 0, 0], f()))  # N: Revealed type is "itertools.batched[builtins.tuple[builtins.int, ...]]"
+
+[builtins fixtures/tuple.pyi]
+
+[case testItertoolsBatched313]
+# flags: --python-version 3.13
+
+from itertools import batched
+
+b = batched([0], 1, strict=True)
+reveal_type(b)  # N: Revealed type is "itertools.batched[tuple[builtins.int]]"
+reveal_type(b.__next__())  # N: Revealed type is "tuple[builtins.int]"
+
+reveal_type(batched([0, 0], 2, strict=True))  # N: Revealed type is "itertools.batched[tuple[builtins.int, builtins.int]]"
+reveal_type(batched([0, 0, 0], 3, strict=True))  # N: Revealed type is "itertools.batched[tuple[builtins.int, builtins.int, builtins.int]]"
+reveal_type(batched([0, 0, 0, 0], 4, strict=True))  # N: Revealed type is "itertools.batched[tuple[builtins.int, builtins.int, builtins.int, builtins.int]]"
+reveal_type(batched([0, 0, 0, 0, 0], 5, strict=True))  # N: Revealed type is "itertools.batched[tuple[builtins.int, builtins.int, builtins.int, builtins.int, builtins.int]]"
+
+reveal_type(batched([0], 2),)  # N: Revealed type is "itertools.batched[builtins.tuple[builtins.int, ...]]"
+reveal_type(batched([0], 2, strict=False))  # N: Revealed type is "itertools.batched[builtins.tuple[builtins.int, ...]]"
+
+def f() -> int:
+    return 3
+
+reveal_type(batched([0, 0, 0], f(), strict=True))  # N: Revealed type is "itertools.batched[builtins.tuple[builtins.int, ...]]"
+
+[builtins fixtures/tuple.pyi]