Make self and cls positional-only in dict constructor methods (#15262)

Author: AlexWaygood

stdlib/builtins.pyi

@@ -1176,9 +1176,9 @@ class dict(MutableMapping[_KT, _VT]):
     # __init__ should be kept roughly in line with `collections.UserDict.__init__`, which has similar semantics
     # Also multiprocessing.managers.SyncManager.dict()
     @overload
-    def __init__(self) -> None: ...
+    def __init__(self, /) -> None: ...
     @overload
-    def __init__(self: dict[str, _VT], **kwargs: _VT) -> None: ...  # pyright: ignore[reportInvalidTypeVarUse]  #11780
+    def __init__(self: dict[str, _VT], /, **kwargs: _VT) -> None: ...  # pyright: ignore[reportInvalidTypeVarUse]  #11780
     @overload
     def __init__(self, map: SupportsKeysAndGetItem[_KT, _VT], /) -> None: ...
     @overload
@@ -1203,7 +1203,7 @@ class dict(MutableMapping[_KT, _VT]):
     def __init__(self: dict[str, str], iterable: Iterable[list[str]], /) -> None: ...
     @overload
     def __init__(self: dict[bytes, bytes], iterable: Iterable[list[bytes]], /) -> None: ...
-    def __new__(cls, *args: Any, **kwargs: Any) -> Self: ...
+    def __new__(cls, /, *args: Any, **kwargs: Any) -> Self: ...
     def copy(self) -> dict[_KT, _VT]: ...
     def keys(self) -> dict_keys[_KT, _VT]: ...
     def values(self) -> dict_values[_KT, _VT]: ...