remove phan as local dev requirement

Author: dirx

composer.json

@@ -29,8 +29,7 @@
     "psr/http-server-handler": "^1.0"
   },
   "require-dev": {
-    "phpunit/phpunit": "^6.5",
-    "phan/phan": "^0.12.9"
+    "phpunit/phpunit": "^6.5"
   },
   "autoload": {
     "psr-4": {