fix type error in test

Author: staabm

tests/end-to-end/regression/6105/IssueTest6105.php

@@ -30,11 +30,11 @@ public function test_1(): void
  public function test_case_2_check(): void
  {
  ob_start();
- header('X-Test', 'Testing');
+ header('X-Test: Testing');
  print 'asd';
  $content = ob_get_clean();
 
  $this->assertSame('asd', $content);
- $this->assertSame(['X-Test'], xdebug_get_headers());
+ $this->assertSame(['X-Test: Testing'], xdebug_get_headers());
  }
 }