[rust]: fix some unuse warniings

frontend/rust-lib/lib-dispatch/src/request/request.rs

@@ -17,6 +17,7 @@ use std::{
 
 #[derive(Clone, Debug, Derivative)]
 pub struct EventRequest {
+    #[allow(dead_code)]
     pub(crate) id: String,
     pub(crate) event: Event,
     #[derivative(Debug = "ignore")]

frontend/rust-lib/lib-sqlite/src/pool.rs

@@ -101,6 +101,7 @@ pub struct DatabaseCustomizerConfig {
     pub(crate) journal_mode: SQLiteJournalMode,
     pub(crate) synchronous: SQLiteSynchronous,
     pub(crate) busy_timeout: i32,
+    #[allow(dead_code)]
     pub(crate) secure_delete: bool,
 }
 

shared-lib/flowy-document-infra/src/core/history.rs

@@ -4,7 +4,10 @@ const MAX_UNDOS: usize = 20;
 
 #[derive(Debug, Clone)]
 pub struct UndoResult {
+    #[allow(dead_code)]
     success: bool,
+
+    #[allow(dead_code)]
     len: usize,
 }
 
@@ -16,6 +19,7 @@ impl UndoResult {
 
 #[derive(Debug, Clone)]
 pub struct History {
+    #[allow(dead_code)]
     cur_undo: usize,
     undos: Vec<Delta>,
     redoes: Vec<Delta>,