Improve time types

src/toggl_api/types.rs

@@ -62,9 +62,9 @@ pub struct Project {
     pub name: String,
     pub active: bool,
     pub color: String,
-    pub at: String,
-    pub server_deleted_at: Option<String>,
-    pub created_at: String,
+    pub at: DateTime<Utc>,
+    pub server_deleted_at: Option<DateTime<Utc>>,
+    pub created_at: DateTime<Utc>,
 
     // cid: Option<serde_json::Value>,
     // wid: i64,