feat: create a task model

src/schema/mod.rs

@@ -6,3 +6,20 @@ diesel::table! {
         title -> Text,
     }
 }
+
+diesel::table! {
+    tasks (id) {
+        id -> Int4,
+        title -> Text,
+        deadline -> Nullable<Date>,
+        category -> Jsonb,
+        project_id -> Nullable<Int4>,
+    }
+}
+
+diesel::joinable!(tasks -> projects (project_id));
+
+diesel::allow_tables_to_appear_in_same_query!(
+    projects,
+    tasks,
+);