wip: print: Add accept_label

Requires version 2.

See flatpak/xdg-desktop-portal#1094.

src/desktop/print.rs

@@ -556,14 +556,24 @@ struct PreparePrintOptions {
     handle_token: HandleToken,
     /// Whether to make the dialog modal.
     modal: Option<bool>,
+    /// Label for the accept button. Mnemonic underlines are allowed.
+    accept_label: Option<String>,
 }
 
 impl PreparePrintOptions {
     /// Sets whether the dialog should be a modal.
+    #[must_use]
     pub fn modal(mut self, modal: impl Into<Option<bool>>) -> Self {
         self.modal = modal.into();
         self
     }
+
+    /// Label for the accept button. Mnemonic underlines are allowed.
+    #[must_use]
+    pub fn accept_label<'a>(mut self, accept_label: impl Into<Option<&'a str>>) -> Self {
+        self.accept_label = accept_label.into().map(ToOwned::to_owned);
+        self
+    }
 }
 
 #[derive(SerializeDict, Type, Debug, Default)]