Add missing requirements

Author: icanhazstring

composer.json

@@ -4,12 +4,14 @@
     "type": "library",
     "require": {
         "php": "^7.1",
-        "symfony/process": "^3.2"
+        "symfony/process": "^3.2",
+        "league/plates": "^3.3"
     },
     "require-dev": {
         "phpunit/phpunit": "^6.1",
         "squizlabs/php_codesniffer": "^3.0",
-        "codeclimate/php-test-reporter": "dev-master"
+        "codeclimate/php-test-reporter": "dev-master",
+        "adlawson/vfs": "^0.12.1"
     },
     "autoload": {
         "psr-4": {