Merge pull request thephpleague#255 from Ocramius/feature/money-v4-support

Allow usage of `moneyphp/money:^4.0.3`

Author: barryvdh

composer.json

@@ -47,7 +47,7 @@
         "php-http/message": "^1.5",
         "php-http/discovery": "^1.14",
         "symfony/http-foundation": "^2.1|^3|^4|^5",
-        "moneyphp/money": "^3.1"
+        "moneyphp/money": "^3.1|^4.0.3"
     },
     "require-dev": {
         "omnipay/tests": "^4.1",