Add guzzle's PSR7 package

Author: mikebronner

composer.json

@@ -28,6 +28,7 @@
         "geocoder-php/chain-provider": "^4.0",
         "geocoder-php/geo-plugin-provider": "^4.0",
         "geocoder-php/google-maps-provider": "^4.0",
+        "guzzlehttp/psr7": "*",
         "illuminate/cache": "5.*",
         "illuminate/support": "5.*",
         "php": "^7.0",