Upgrade of Drone.io (#2)

Fix [#1](issues/1)

composer.json

@@ -27,6 +27,7 @@
 		}
 	},
     "require": {
+		"php": "^7.1",
         "twig/twig": "^2.7",
         "psr/simple-cache": "^1.0",
         "psr/log": "^1.1",
@@ -35,7 +36,7 @@
     "require-dev": {
         "squizlabs/php_codesniffer": "^3.4",
         "symfony/var-dumper": "^4.2",
-        "phpunit/phpunit": "^8.1",
+        "phpunit/phpunit": "7.*",
         "codacy/coverage": "^1.4",
         "phpmd/phpmd": "^2.6",
         "phpstan/phpstan": "^0.11.5"