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

Beginne damit, die bereitgestellte Python-Reproduktion auszuführen, und vergleiche ihr Narrowing-Verhalten mit dem entsprechenden expliziten Literal-Fall. Die Arbeit ist abgeschlossen, wenn die auf Final basierende Union in den beiden Zweigen zu TXTRecord und ARecord eingeengt wird, ohne die gemeldeten Attributfehler zu erzeugen.