Ignore poor suggestion from branches_sharing_code lint

rust-lang/rust-clippy#7054

    error: all if blocks contain the same code at the end
        --> serde_derive/src/de.rs:2160:5
         |
    2160 | /         &fallthrough_arm_tokens
    2161 | |     };
         | |_____^
         |
    note: the lint level is defined here
        --> serde_derive/src/lib.rs:18:9
         |
    18   | #![deny(clippy::all, clippy::pedantic)]
         |         ^^^^^^^^^^^
         = note: `#[deny(clippy::branches_sharing_code)]` implied by `#[deny(clippy::all)]`
         = note: The end suggestion probably needs some adjustments to use the expression result correctly
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#branches_sharing_code
    help: consider moving the end statements out like this
         |
    2160 |     }
    2161 |     &fallthrough_arm_tokens;
         |

Author: dtolnay

serde_derive/src/lib.rs

@@ -18,6 +18,8 @@
 #![deny(clippy::all, clippy::pedantic)]
 // Ignored clippy lints
 #![allow(
+    // clippy false positive: https://github.com/rust-lang/rust-clippy/issues/7054
+    clippy::branches_sharing_code,
     clippy::cognitive_complexity,
     clippy::enum_variant_names,
     // clippy bug: https://github.com/rust-lang/rust-clippy/issues/6797