Clippyfy (#6341)

* Add clippy config and remove .cargo from gitignore

* first fixes

* Clippyfied

* Add clippy CI job

* comment out rusty-cachier

* minor

* fix ci

* remove DAG from check-dependent-project

* add DAG to clippy

Co-authored-by: alvicsam <alvicsam@gmail.com>

polkadot/erasure-coding/src/lib.rs

@@ -216,7 +216,7 @@ pub struct Branches<'a, I> {
 impl<'a, I: AsRef<[u8]>> Branches<'a, I> {
 	/// Get the trie root.
 	pub fn root(&self) -> H256 {
-		self.root.clone()
+		self.root
 	}
 }