`functools.lru_cache` wrapped function with TypeVar has wrong return type.

Hi,

I think there is a problem when using functools.lru_cache (and functools.cache). When the decorated function uses a TypeVar for typing arguments and return type, the wrapped function returend by functools.lru_cache has wrong (or unresolved) types.
This is not the case when replacing the TypeVar with an explicit type. See the mwe below. Thx.

import functools
from typing import TypeVar

_T = TypeVar("_T")


def my_func(elem: _T) -> list[_T]:
    return [elem]
    
my_func_cached = functools.lru_cache(my_func)

a = my_func("a")
reveal_type(a)  # Revealed type is "builtins.list[builtins.str*]"
a_c = my_func_cached("a")

# ERROR: this should be "builtins.list*[builtins.str]"
reveal_type(a_c)  # Revealed type is "builtins.list*[_T`-1]"


# this works

def my_func_str(elem: str) -> list[str]:
    return [elem]
    
my_func_str_cached = functools.lru_cache(my_func_str)

a_str = my_func_str("a")
reveal_type(a_str)  # Revealed type is "builtins.list[builtins.str]"
a_str_c = my_func_str_cached("a")
reveal_type(a_str_c)  # Revealed type is "builtins.list*[builtins.str]"

Running:
Python 3.10.1
mypy 0.931
Linux 5.16.0-arch1-1

提供された最小限の例を mypy 0.931 で使って問題を再現し、その後 functools.lru_cache と functools.cache の typeshed 定義を調査します。キャッシュされたジェネリック関数が未解決の TypeVar ではなく list[str] を示し、明示的な str の例が引き続き動作すれば作業は完了です。