Update MergeTools

Changed the for() statement as per conversation

Author: HighnessAtharva

Strings/MergeTools

@@ -9,7 +9,7 @@ Problem   : https://www.hackerrank.com/challenges/merge-the-tools/
 from collections import OrderedDict
 
 def merge_the_tools(string, k):
-    for i in range(0, len(string), k):
+    for i in range(0, len(string)-k+1, k):
         print(''.join(OrderedDict.fromkeys(string[i:i + k])))
 
 if __name__ == '__main__':