Ignore buggy doc_link_with_quotes clippy lint

rust-lang/rust-clippy#8961

    error: possible intra-doc link using quotes instead of backticks
       --> serde_test/src/token.rs:277:5
        |
    277 |     /// let vec = vec!['a', 'b', 'c'];
        |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        |
        = note: `-D clippy::doc-link-with-quotes` implied by `-D clippy::pedantic`
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#doc_link_with_quotes

serde_test/src/lib.rs

@@ -153,6 +153,7 @@
     feature = "cargo-clippy",
     allow(
         cloned_instead_of_copied,
+        doc_link_with_quotes, // https://github.com/rust-lang/rust-clippy/issues/8961
         empty_line_after_outer_attr,
         manual_assert,
         missing_docs_in_private_items,