Reformat use declarations.

The previous commit updated `rustfmt.toml` appropriately. This commit is
the outcome of running `x fmt --all` with the new formatting options.

compiler/rustc_parse_format/src/lib.rs

@@ -15,16 +15,14 @@
 )]
 // tidy-alphabetical-end
 
+use std::{iter, str, string};
+
 use rustc_lexer::unescape;
 pub use Alignment::*;
 pub use Count::*;
 pub use Piece::*;
 pub use Position::*;
 
-use std::iter;
-use std::str;
-use std::string;
-
 // Note: copied from rustc_span
 /// Range inside of a `Span` used for diagnostics when we only have access to relative positions.
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]