stop using deprecated PHPUnit APIs

Author: xabbuh

Test/HttpClientTestCase.php

@@ -844,7 +844,7 @@ public function testProxy()
 
         $body = $response->toArray();
         $this->assertSame('localhost:8057', $body['HTTP_HOST']);
-        $this->assertRegexp('#^http://(localhost|127\.0\.0\.1):8057/$#', $body['REQUEST_URI']);
+        $this->assertMatchesRegularExpression('#^http://(localhost|127\.0\.0\.1):8057/$#', $body['REQUEST_URI']);
 
         $response = $client->request('GET', 'http://localhost:8057/', [
             'proxy' => 'http://foo:b%3Dar@localhost:8057',