when Mojolicious 4.0 some method deprecated and removed from mojolicious, Fix it !

The following method is removed from mojolicious when version is 4.0:

- render_text => https://github.com/kraih/mojo/blob/master/Changes#L30
- is_dynamic => https://github.com/kraih/mojo/blob/master/Changes#L34

I fix this, just a little work, hope you can merge it earlier :)