Upgrade to rust 1.39.0 (#6939)

* Upgrade to rust 1.39.0

* 1.39.0 clippy

genesis/src/main.rs

@@ -83,6 +83,7 @@ pub fn add_genesis_accounts(file: &str, genesis_config: &mut GenesisConfig) -> i
     Ok(())
 }
 
+#[allow(clippy::cognitive_complexity)]
 fn main() -> Result<(), Box<dyn error::Error>> {
     let default_bootstrap_leader_lamports = &sol_to_lamports(500.0).to_string();
     let default_bootstrap_leader_stake_lamports = &sol_to_lamports(0.5).to_string();