[schema][database] Fix nfs regex

beat/core/schema/database/1.json

@@ -9,7 +9,7 @@
 
     "root_folder": {
       "type": "string",
-      "pattern": "^((file://)?(/[^/]+)+|nfs://[a-z0-9.-_]+:(/[^/]+)+)$"
+      "pattern": "^((file://)?(/[^/]+)+|nfs://[a-z0-9._-]+:(/[^/]+)+)$"
     },
 
     "protocols": {