require-dev section updated

Author: s3b4stian

composer.json

@@ -18,13 +18,16 @@
         "php": "^7.0"
     },
     "require-dev": {
-        "infection/infection": "^0.7",
-        "phpstan/phpstan": "^0.9",
-        "phpunit/phpunit": "^6.0"
+        "infection/infection": "^0.9",
+        "phpstan/phpstan": "^0.10",
+        "phpunit/phpunit": "^7.0"
     },
     "autoload": {
         "psr-4": {
             "Linna\\": "src/"
         }
+    },
+    "autoload-dev": {
+        "classmap": ["tests/"]
     }
 }