Reformat imports to a consistent style for imports

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

sdk/program/src/slot_hashes.rs

@@ -2,8 +2,10 @@
 //!
 //! this account carries the Bank's most recent bank hashes for some N parents
 //!
-use crate::hash::Hash;
-use std::{iter::FromIterator, ops::Deref};
+use {
+    crate::hash::Hash,
+    std::{iter::FromIterator, ops::Deref},
+};
 
 pub const MAX_ENTRIES: usize = 512; // about 2.5 minutes to get your vote in
 
@@ -54,8 +56,7 @@ impl Deref for SlotHashes {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
-    use crate::hash::hash;
+    use {super::*, crate::hash::hash};
 
     #[test]
     fn test() {