refactor: move dynamic_label.rs to dynamic_string.rs and fix failing test

src/modules/custom.rs

@@ -2,7 +2,7 @@ use crate::config::CommonConfig;
 use crate::modules::{Module, ModuleInfo, ModuleUpdateEvent, ModuleWidget, WidgetContext};
 use crate::popup::{ButtonGeometry, Popup};
 use crate::script::Script;
-use crate::widgets::DynamicString;
+use crate::dynamic_string::DynamicString;
 use color_eyre::{Report, Result};
 use gtk::prelude::*;
 use gtk::{Button, Label, Orientation};