fix: preserve Unicode characters in class names for --filter matching

tests/.snapshots/success.txt

@@ -1775,6 +1775,10 @@
   - todo
   - todo in parallel
 
+   PASS  Tests\Visual\UnicodeFilename
+  ✓ filter works with unicode characters in filename
+  ✓ filter with unicode regex matches unicode filename
+
    WARN  Tests\Visual\Version
   - visual snapshot of help command output
 
@@ -1782,4 +1786,4 @@
   ✓ pass with dataset with ('my-datas-set-value')
   ✓ within describe → pass with dataset with ('my-datas-set-value')
 
-  Tests:    2 deprecated, 4 warnings, 5 incomplete, 2 notices, 39 todos, 35 skipped, 1188 passed (2813 assertions)
+  Tests:    2 deprecated, 4 warnings, 5 incomplete, 2 notices, 39 todos, 35 skipped, 1190 passed (2818 assertions)

tests/.tests/StraßenTest.php

@@ -0,0 +1,3 @@
+<?php
+
+it('tests unicode filename with ß')->assertTrue(true);

tests/Visual/UnicodeFilename.php

@@ -0,0 +1,37 @@
+<?php
+
+use Symfony\Component\Process\Process;
+
+test('filter works with unicode characters in filename', function () {
+    $process = new Process([
+        'php',
+        'bin/pest',
+        'tests/.tests/StraßenTest.php',
+        '--colors=never',
+    ], dirname(__DIR__, 2), ['COLLISION_PRINTER' => 'DefaultPrinter', 'COLLISION_IGNORE_DURATION' => 'true']);
+
+    $process->run();
+
+    $output = $process->getOutput();
+
+    expect($output)->toContain('StraßenTest');
+    expect($output)->toContain('tests unicode filename');
+    expect($output)->toContain('1 passed');
+})->skipOnWindows();
+
+test('filter with unicode regex matches unicode filename', function () {
+    $process = new Process([
+        'php',
+        'bin/pest',
+        '--filter=.*Straß.*',
+        'tests/.tests/',
+        '--colors=never',
+    ], dirname(__DIR__, 2), ['COLLISION_PRINTER' => 'DefaultPrinter', 'COLLISION_IGNORE_DURATION' => 'true']);
+
+    $process->run();
+
+    $output = $process->getOutput();
+
+    expect($output)->toContain('StraßenTest');
+    expect($output)->toContain('1 passed');
+})->skipOnWindows();