Merge pull request #870 from bshaffer/bump-google-auth

bump google auth to 0.6

Author: bshaffer

composer.json

@@ -7,7 +7,7 @@
     "license": "Apache-2.0",
     "require": {
         "php": ">=5.4",
-        "google/auth": "0.5",
+        "google/auth": "0.6",
         "firebase/php-jwt": "~2.0|~3.0",
         "monolog/monolog": "^1.17",
         "phpseclib/phpseclib": "~2.0",