Byte strings aren't docstrings (#8350)

We previously incorrectly treated byte strings in docstring position as
docstrings because black does so
(https://github.com/astral-sh/ruff/pull/8283#discussion_r1375682931,
https://github.com/psf/black/issues/4002), even CPython doesn't
recognize them:

```console
$ python3.12
Python 3.12.0 (main, Oct  6 2023, 17:57:44) [GCC 11.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> def f():
...     b""" a"""
...
>>> print(str(f.__doc__))
None
```

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crates/ruff_python_formatter/src/statement/suite.rs

@@ -554,7 +554,6 @@ impl<'a> DocstringStmt<'a> {
 
         match value.as_ref() {
             Expr::StringLiteral(value) if !value.implicit_concatenated => Some(DocstringStmt(stmt)),
-            Expr::BytesLiteral(value) if !value.implicit_concatenated => Some(DocstringStmt(stmt)),
             _ => None,
         }
     }