Upgrade league/commonmark to avoid security advisory

Signed-off-by: Micheal Mand <micheal@kmdwebdesigns.com>

composer.json

@@ -35,7 +35,7 @@
         "beyondcode/laravel-dump-server": "^1.0",
         "filp/whoops": "^2.0",
         "fzaninotto/faker": "^1.4",
-        "league/commonmark": "^0.15.4",
+        "league/commonmark": "^0.18.3",
         "league/flysystem-aws-s3-v3": "^1.0",
         "mockery/mockery": "^1.0",
         "nunomaduro/collision": "^2.0",