Update `SocketType.recv` (&other) signatures to use PEP570

[jakkdl]

python/typeshed#11250 changed the signatures of SocketType.recv and friends, so it should now be possible to change

trio/src/trio/_socket.py

Lines 1115 to 1129 in 4e979bf

	# Not possible to typecheck with a Callable (due to DefaultArg), nor with a
	# callback Protocol (https://github.com/python/typing/discussions/1040)
	# but this seems to work. If not explicitly defined then pyright --verifytypes will
	# complain about AmbiguousType
	if TYPE_CHECKING:
	def recv(__self, __buflen: int, __flags: int = 0) -> Awaitable[bytes]: ...
	# _make_simple_sock_method_wrapper is typed, so this checks that the above is correct
	# this requires that we refrain from using `/` to specify pos-only
	# args, or mypy thinks the signature differs from typeshed.
	recv = _make_simple_sock_method_wrapper(
	_stdlib_socket.socket.recv,
	_core.wait_readable,
	)

although I'm surprised that mypy haven't started complaining from bumping typeshed. Maybe they did some backwards compatibility thing? Or haven't bumped typeshed?