Add multibyte string tests for TitleCase and UpperCaseFirst

tests/src/Unit/TitleCaseTest.php

@@ -31,6 +31,7 @@ class TitleCaseTest extends TokenModifierTestCase {
     $data['basic'] = ['hello world!', 'Hello World!'];
     $data['already capitalised'] = ['It\'s Working?', 'It\'s Working?'];
     $data['everything else capitalised'] = ['cAPITALISE eVERYTHING', 'CAPITALISE EVERYTHING'];
+    $data['multibyte'] = ['čhecking multibyte ūnderway...', 'Čhecking Multibyte Ūnderway...'];
     return $data;
   }
 

tests/src/Unit/UpperCaseFirstTest.php

@@ -31,6 +31,7 @@ class UpperCaseFirstTest extends TokenModifierTestCase {
     $data['basic'] = ['hello world!', 'Hello world!'];
     $data['already capitalised'] = ['Working?', 'Working?'];
     $data['everything else capitalised'] = ['cAPITALISE', 'CAPITALISE'];
+    $data['multibyte'] = ['čhecking multibyte ūnderway...', 'Čhecking multibyte ūnderway...'];
     return $data;
   }