Ignore buggy collapsible_match clippy lint

rust-lang/rust-clippy#7575

    error: unnecessary nested `if let` or `match`
        --> src/generics.rs:1190:33
         |
    1190 | / ...                   if let TokenTree::Punct(q) = token {
    1191 | | ...                       if q.as_char() == '?' {
    1192 | | ...                           if let Some(TokenTree::Ident(c)) = iter.peek() {
    1193 | | ...                               if c == "const" {
    ...    |
    1201 | | ...                       }
    1202 | | ...                   }
         | |_______________________^
         |
         = note: `-D clippy::collapsible-match` implied by `-D clippy::all`
    help: the outer pattern can be modified to include the inner pattern
        --> src/generics.rs:1189:44
         |
    1189 | ...                   while let Some(token) = iter.next() {
         |                                      ^^^^^ replace this binding
    1190 | ...                       if let TokenTree::Punct(q) = token {
         |                                  ^^^^^^^^^^^^^^^^^^^ with this pattern
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_match

Author: dtolnay

src/lib.rs

@@ -255,6 +255,7 @@
 #![allow(non_camel_case_types)]
 // Ignored clippy lints.
 #![allow(
+    clippy::collapsible_match, // https://github.com/rust-lang/rust-clippy/issues/7575
     clippy::doc_markdown,
     clippy::eval_order_dependence,
     clippy::inherent_to_string,