fixed the code to ensure no use of repeat was used by using "for"

Author: HM-127BTY

practice-tdd/repeat-str.js

@@ -4,5 +4,9 @@ export function repeatStr(str, count) {
   if (count < 0) {
     throw new Error("negative counts are not valid");
   }
-  return str.repeat(count);
+  let result = "";
+  for (let i = 0; i < count; i++) {
+    result += str;
+  }
+  return result;
 }