Fix quotes, format.
diff --git a/lib/src/rules/prefer_single_quotes.dart b/lib/src/rules/prefer_single_quotes.dart
index bc3257f..c39a021 100644
--- a/lib/src/rules/prefer_single_quotes.dart
+++ b/lib/src/rules/prefer_single_quotes.dart
@@ -8,8 +8,7 @@
 
 import '../analyzer.dart';
 
-const _desc =
-    r"Only use double quotes for strings containing single quotes.";
+const _desc = r'Only use double quotes for strings containing single quotes.';
 
 const _details = '''