fix: upgrade mt dom api

[CurryPseudo]

Fix compile error:

error[E0599]: no method named `text` found for reference `&Node<&str, &str, svgbob::sauron::prelude::Leaf, &str, AttributeValue<()>>` in the current scope
   --> src\textproc.rs:297:47
    |
297 |                     if let Some(text) = child.text() {
    |                                               ^^^^ method not found in `&Node<&str, &str, svgbob::sauron::prelude::Leaf, &str, AttributeValue<()>>`

[yvt]

Thanks!