Reformat imports to a consistent style for imports

rustfmt.toml configuration:
  imports_granularity = "One"
  group_imports = "One"

program-runtime/src/timings.rs

@@ -1,5 +1,4 @@
-use solana_sdk::pubkey::Pubkey;
-use std::collections::HashMap;
+use {solana_sdk::pubkey::Pubkey, std::collections::HashMap};
 
 #[derive(Default, Debug)]
 pub struct ProgramTiming {