rustfmt: Drop routing/mod.rs from exclusion list

Author: tnull

rustfmt_excluded_files

@@ -66,7 +66,6 @@ lightning/src/onion_message/messenger.rs
 lightning/src/onion_message/mod.rs
 lightning/src/onion_message/offers.rs
 lightning/src/onion_message/packet.rs
-lightning/src/routing/mod.rs
 lightning/src/util/atomic_counter.rs
 lightning/src/util/base32.rs
 lightning/src/util/byte_utils.rs