fix for Mojolicious 5.54

Hello,

This recent change https://github.com/kraih/mojo/commit/27a351852423d197ea1e8d42adcc7fc3eb81fa77 is causing tests to fail for Mojolicious::Plugin::YamlConfig with perl 5.20.1 and Mojolicious 5.54.

The attached change fixes it.

best,
Brian