ParserSyntaxError for "unmatched ']'" faults wrong location

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.