Update master php testing versions

Signed-off-by: Joas Schilling <coding@schilljs.com>

tests/phpunit.xml

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8" ?>
 <phpunit bootstrap="bootstrap.php"
 		 verbose="true"
+		 convertDeprecationsToExceptions="true"
 		 timeoutForSmallTests="900"
 		 timeoutForMediumTests="900"
 		 timeoutForLargeTests="900"