Fix PEP 695 generic alias parameters being bound by position - #1275

import msgspec
import msgspec.inspect as mi

type Swap[A, B] = dict[B, A]
dec = msgspec.json.Decoder(Swap[int, str])
print(mi.type_info(Swap[int, str]))
print(dec.decode(b'{"x": 1}'))

# on upstream this resolves to dict[int, str] and fails:
"""
DictType(key_type=IntType(...), value_type=StrType(...), ...)
msgspec.ValidationError: Expected `int`, got `str` - at `key` in `$`

DictType(key_type=StrType(...), value_type=IntType(...), ...)
{'x': 1}
"""

type D[T, **P] = Callable[P, T]
D[int, [str]]  # upstream: TypeError, bound as (P, T)

type Last[T, *Ts] = tuple[*Ts, T]
Last[int, str, float]  # upstream: tuple[int, str, float], should be tuple[str, float, int]