slightly improve performance by replacing iterators with owning for loops

src/test.rs

@@ -0,0 +1,14 @@
+extern crate test;
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::response_deserializer;
+    use test::Bencher;
+
+    #[bench]
+    fn loops(b: &mut Bencher) {
+        let search_result = std::fs::read_to_string("test_data/search_result.json").unwrap();
+        b.iter(|| response_deserializer::deserializer(&search_result));
+    }
+}