Auto merge of #51609 - dscorbett:is_numeric, r=alexcrichton

Auto merge of #51609 - dscorbett:is_numeric, r=alexcrichton

Treat gc=No characters as numeric

[`char::is_numeric`](https://doc.rust-lang.org/std/primitive.char.html#method.is_numeric) and [`char::is_alphanumeric`](https://doc.rust-lang.org/std/primitive.char.html#method.is_alphanumeric) are documented to be defined “in terms of the Unicode General Categories 'Nd', 'Nl', 'No'”, but unicode.py does not group 'No' with the other 'N' categories. These functions therefore currently return `false` for characters like ⟨¾⟩ and ⟨①⟩.