Updated security-checker to version 5, 4 is not working any more (#29)

Author: brammittendorff

composer.json

@@ -43,7 +43,7 @@
     "scheb/tombstone-analyzer": "^0.3",
     "sebastian/phpcpd": "^3.0",
     "seld/jsonlint": "^1.6",
-    "sensiolabs/security-checker": "^4.1",
+    "sensiolabs/security-checker": "^5.0",
     "sllh/composer-versions-check": "^2.0",
     "squizlabs/php_codesniffer": "^3.2"
   },