ParserSyntaxError for "unmatched ']'" faults wrong location

[thatch]

I suspect this is an upstream issue, but documenting the repro so we can know if it gets fixed:

"""docstring"""
import a
import b
def foo(data: str) -> tuple[str, ...], frozenset[str]]:
  pass

(note too many close brackets at the end of the def line)

libcst._exceptions.ParserSyntaxError: Syntax Error @ 1:1.
tokenizer error: unmatched ']'

"""docstring"""
^

faults the first line of the file, when there is clearly one specific byte that can be faulted -- the extra close bracket.

[thatch]

Hit this again today via ufmt, forgot I filed this one before :)