add latest price route

src/variant.rs

@@ -225,14 +225,14 @@ impl Variant {
         )
     }
 
-    pub async fn price_history_by_origin(&self, origin: &str) -> Vec<Price> {
+    pub async fn price_history_by_origin(&self, origin: &str, limit: Option<i64>) -> Vec<Price> {
         Transaction::find(
             doc! {
                 "item": &self.item,
                 "variant": &self.variant,
                 "origin": origin
             },
-            None,
+            limit,
             Some(sort_by_timestamp()),
         )
         .await