Relax 1 test failing with latest PHP versions

Related to php bug symfony#52646 which is fixed in 5.6.25RC1, 7.0.10RC1, 7.1.0beta2

Author: remicollet

src/Symfony/Component/VarDumper/Tests/Caster/SplCasterTest.php

@@ -94,10 +94,10 @@ public function testCastFileObject()
   file: true
   dir: false
   link: false
-%AcsvControl: array:2 [
+%AcsvControl: array:%d [
     0 => ","
     1 => """
-  ]
+%A]
   flags: DROP_NEW_LINE|SKIP_EMPTY
   maxLineLen: 0
   fstat: array:26 [