Prevent failing filter handling on 'Test' instances

Make sure the 'processSuiteFilters' method is only called
for 'TestSuite' objects not for 'Test' objects. To achieve this,
the 'processSuiteFilters' method call got  moved to an existing
type check.

Fix issue #3254

src/TextUI/TestRunner.php

@@ -190,8 +190,6 @@ public function doRun(Test $suite, array $arguments = [], $exit = true)
 
         $this->handleConfiguration($arguments);
 
-        $this->processSuiteFilters($suite, $arguments);
-
         if (isset($arguments['bootstrap'])) {
             $GLOBALS['__PHPUNIT_BOOTSTRAP'] = $arguments['bootstrap'];
         }
@@ -540,6 +538,7 @@ public function doRun(Test $suite, array $arguments = [], $exit = true)
         $result->setTimeoutForLargeTests($arguments['timeoutForLargeTests']);
 
         if ($suite instanceof TestSuite) {
+            $this->processSuiteFilters($suite, $arguments);
             $suite->setRunTestInSeparateProcess($arguments['processIsolation']);
         }