Auto merge of #78636 - dtolnay:puncteq, r=petrochenkov

Auto merge of #78636 - dtolnay:puncteq, r=petrochenkov

Add PartialEq<char> for proc_macro::Punct

`punct.as_char() == '░'` is pervasive when parsing anything involving punct. I think `punct == '░'` is sufficiently unambiguous that it makes sense to provide the impl.

https://github.com/rust-lang/rust/blob/1899c489d4c30b2640d30b77ac04f0a548834d81/library/proc_macro/src/quote.rs#L79
https://github.com/rust-lang/rust/blob/1899c489d4c30b2640d30b77ac04f0a548834d81/library/proc_macro/src/quote.rs#L83
https://github.com/rust-lang/rust/blob/1899c489d4c30b2640d30b77ac04f0a548834d81/src/test/ui/suggestions/auxiliary/issue-61963.rs#L26
https://github.com/rust-lang/rust/blob/1899c489d4c30b2640d30b77ac04f0a548834d81/src/test/ui/proc-macro/auxiliary/three-equals.rs#L23