Remove empty __init__ methods (#8816)

stdlib/formatter.pyi

@@ -64,7 +64,6 @@ class AbstractFormatter:
     def assert_line_data(self, flag: int = ...) -> None: ...
 
 class NullWriter:
-    def __init__(self) -> None: ...
     def flush(self) -> None: ...
     def new_alignment(self, align: str | None) -> None: ...
     def new_font(self, font: _FontType) -> None: ...