Ignore unconditional_recursion clippy lint due to false positive

rust-lang/rust-clippy#12133

    warning: function cannot return without recursing
      --> src/lifetime.rs:90:5
       |
    90 | /     fn eq(&self, other: &Lifetime) -> bool {
    91 | |         self.ident.eq(&other.ident)
    92 | |     }
       | |_____^
       |
    note: recursive call site
      --> src/lifetime.rs:91:9
       |
    91 |         self.ident.eq(&other.ident)
       |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unconditional_recursion
       = note: `-W clippy::unconditional-recursion` implied by `-W clippy::all`
       = help: to override `-W clippy::all` add `#[allow(clippy::unconditional_recursion)]`

src/lib.rs

@@ -292,6 +292,7 @@
     clippy::too_many_arguments,
     clippy::too_many_lines,
     clippy::trivially_copy_pass_by_ref,
+    clippy::unconditional_recursion, // https://github.com/rust-lang/rust-clippy/issues/12133
     clippy::uninhabited_references,
     clippy::uninlined_format_args,
     clippy::unnecessary_box_returns,