sc-cli: Remove SubstrateCli::native_runtime_version function (#14511)

The native runtime will be removed in the near future and thus this function will not be required
anymore.

\# Code changes

Downstream users just need to remove `native_runtime_version` from their implementation of the
`SubstrateCli` trait.

substrate/bin/node/cli/src/command.rs

@@ -26,7 +26,7 @@ use frame_benchmarking_cli::*;
 use kitchensink_runtime::{ExistentialDeposit, RuntimeApi};
 use node_executor::ExecutorDispatch;
 use node_primitives::Block;
-use sc_cli::{ChainSpec, Result, RuntimeVersion, SubstrateCli};
+use sc_cli::{Result, SubstrateCli};
 use sc_service::PartialComponents;
 use sp_keyring::Sr25519Keyring;
 
@@ -79,10 +79,6 @@ impl SubstrateCli for Cli {
 		};
 		Ok(spec)
 	}
-
-	fn native_runtime_version(_: &Box<dyn ChainSpec>) -> &'static RuntimeVersion {
-		&kitchensink_runtime::VERSION
-	}
 }
 
 /// Parse command line arguments into service configuration.