Fix unneeded imports (#52)

diff --git a/test/characters_test.dart b/test/characters_test.dart
index 03c9adf..98aa2e2 100644
--- a/test/characters_test.dart
+++ b/test/characters_test.dart
@@ -4,12 +4,10 @@
 
 import "dart:math";
 
+import "package:characters/characters.dart";
 import "package:test/test.dart";
 
-import "package:characters/characters.dart";
-
 import "src/unicode_tests.dart";
-import "src/unicode_grapheme_tests.dart";
 import "src/various_tests.dart";
 
 late Random random;