Fix updated clippy grumbles (#733)

* Revert "Pin Rust Nightly to 2020-12-17 (#652)"

This reverts commit e54e6f7e3d34c28d698e637f9099162b3c1917e9.

* fix clippy

* clippy again

* more clippy in test code

* and new cargo fmt

* another try

bridges/modules/substrate/src/mock.rs

@@ -19,6 +19,8 @@
 //! Includes some useful testing types and functions.
 
 #![cfg(test)]
+// From construct_runtime macro
+#![allow(clippy::from_over_into)]
 
 use crate::{BridgedBlockHash, BridgedBlockNumber, BridgedHeader, Config};
 use bp_runtime::Chain;