fix test to avoid deprecation warning and ignore indirect deprecations

Author: dbu

.travis.yml

@@ -9,6 +9,7 @@ env:
   global:
     - VARNISH_VERSION=5.1
     - SYMFONY_PHPUNIT_VERSION=8
+    - SYMFONY_DEPRECATIONS_HELPER="max[self]=0"
     - DEPENDENCIES="toflar/psr6-symfony-http-cache-store:^2.2.0"
 
 matrix:

tests/Unit/ProxyClient/HttpDispatcherTest.php

@@ -203,7 +203,7 @@ public function testSetBasePathWithPath()
             'http://fos.lo/my/path',
             $this->httpClient
         );
-        $request = $this->messageFactory->createRequest('PURGE', 'append');
+        $request = $this->messageFactory->createRequest('PURGE', '/append');
         $httpDispatcher->invalidate($request);
         $httpDispatcher->flush();