Pygments `Formatter.__init__` overloads do not work as intended

In #6819 pygments.formatter.Formatter was made generic to improve the type safety:

_T = TypeVar("_T", str, bytes)

class Formatter(Generic[_T]):
    @overload
    def __init__(self: Formatter[str], *, encoding: None = ..., outencoding: None = ..., **options) -> None: ...
    @overload
    def __init__(self: Formatter[bytes], *, encoding: str, outencoding: None = ..., **options) -> None: ...
    @overload
    def __init__(self: Formatter[bytes], *, encoding: None = ..., outencoding: str, **options) -> None: ...

Apparently this was never tested, since it does not actually work:

from pygments.formatters.html import HtmlFormatter

reveal_type(HtmlFormatter())
reveal_type(HtmlFormatter(encoding='utf-8'))

$ mypy foo.py
foo.py:3: note: Revealed type is "pygments.formatters.html.HtmlFormatter[builtins.str*]"
foo.py:4: note: Revealed type is "pygments.formatters.html.HtmlFormatter[builtins.str*]"
$ pyright foo.py
  /tmp/foo.py:3:13 - information: Type of "HtmlFormatter(encoding='utf-8')" is "HtmlFormatter[Unknown]"
  /tmp/foo.py:4:13 - information: Type of "HtmlFormatter()" is "HtmlFormatter[Unknown]"

The intention of the overloads is that HtmlFormatter(encoding='utf-8') should be of type HtmlFormatter[builtins.bytes].

I am not sure if this is a mypy bug or if such overload inference should even work in the first place (given that pyright also infers the type variable to be Unknown: https://github.com/microsoft/pyright/issues/3146).

Inizia con gli overload di Formatter introdotti in #6819 e con l'entry point HtmlFormatter. Riproduci i due esempi di reveal_type con mypy e pyright, quindi determina se le dichiarazioni degli overload o il comportamento del checker impediscono a encoding='utf-8' di inferire HtmlFormatter[bytes]. Il lavoro è completato quando i tipi inferiti previsti sono supportati oppure la limitazione è documentata chiaramente.