Final (context-sensitive Literal) doesn't support type narrowing

Bug Report

Maybe there's a reason this is not supported, but at a quick look it seems like it should work. When a union of context-sensitive Literals are used, it fails to perform type narrowing, whereas explicit Literals do work.

To Reproduce

from typing import Final, Literal

class TXTRecord:
    type: Final = "TXT"
    text: str = "Foo"

class ARecord:
    type: Final = "A"
    host: str = "192.168.1.1"

record: TXTRecord | ARecord
reveal_type(record.type)
if record.type == "TXT":
    print(record.text)  # error with Final, but not with Literal
else:
    print(record.host)  # error with Final, but not with Literal

Inizia eseguendo la riproduzione Python fornita e confronta il suo comportamento di narrowing con il caso equivalente di Literal esplicito. Il lavoro è completato quando l’unione basata su Final viene ristretta a TXTRecord e ARecord nei due rami senza produrre gli errori di attributo segnalati.