feat(backend) scheduler rewrite (deadlock for now)

backend/server/src/scheduler/tasks/mod.rs

@@ -1,8 +1,11 @@
+use std::pin::Pin;
+
 use chrono::{DateTime, Utc};
 
+pub mod async_basic;
 pub mod basic;
 
 pub trait CronTask: Send + Sync {
     fn get_next_execution(&self) -> Option<DateTime<Utc>>;
-    fn call(&self);
+    fn call(&self) -> Pin<Box<dyn Future<Output = ()> + Send + '_>>;
 }