bump dep versions + fix phpmailer usage (#144)

Author: Nakiami

composer.json

@@ -18,11 +18,11 @@
     "ircmaxell/password-compat": "dev-master",
     "ircmaxell/random-lib": "1.2.*",
     "google/recaptcha": "~1.1",
-    "phpmailer/phpmailer": "5.*",
+    "phpmailer/phpmailer": "6.*",
     "pear/cache_lite": "~1.8",
     "aws/aws-sdk-php": "3.*"
   },
   "require-dev": {
-    "codeception/codeception": "2.*"
+    "codeception/codeception": "^4.0"
   }
 }