Tweak travis and appveyor for Symfony 4

Author: nicolas-grekas

composer.json

@@ -17,7 +17,7 @@
     ],
     "require": {
         "php": "^7.1.3",
-        "symfony/options-resolver": "~2.8|~3.0|~4.0",
+        "symfony/options-resolver": "~3.4|~4.0",
         "ext-ldap": "*"
     },
     "autoload": {