Ignore unnested_or_patterns suggesting unstable code

Clippy bug: https://github.com/rust-lang/rust-clippy/issues/5704

serde_derive/src/lib.rs

@@ -24,7 +24,9 @@
     clippy::too_many_arguments,
     clippy::trivially_copy_pass_by_ref,
     clippy::used_underscore_binding,
-    clippy::wildcard_in_or_patterns
+    clippy::wildcard_in_or_patterns,
+    // clippy bug: https://github.com/rust-lang/rust-clippy/issues/5704
+    clippy::unnested_or_patterns,
 )]
 // Ignored clippy_pedantic lints
 #![allow(