Merge pull request #32 from rebuy-de/fix-composer

Allow monolog versions >= 1.21

Author: aliabbasrizvi

composer.json

@@ -14,7 +14,7 @@
     "justinrainbow/json-schema": "^1.6 || ^2.0 || ^4.0",
     "lastguest/murmurhash": "1.3.0",
     "guzzlehttp/guzzle": "~5.3|~6.2",
-    "monolog/monolog": "1.21.0"
+    "monolog/monolog": "~1.21"
   },
   "require-dev": {
     "phpunit/phpunit": "~4.8|~5.0",