Fix #FIX-NEEDED

[Agrover112]

👟 Reproduction steps

Implemented in: mulit_mutattion in ga_utils.py Can be tested by replacing mutation with multi_mutation in ga.py.

👍 Expected behavior

Mulit_mutattion in ga_utils.py should change N bits as selected. [1,2,3,4] for 2 bits could be: [1,3,3,5]

👎 Actual Behavior

Mulit_mutattion in ga_utils.py doesn't work as expected. Gives an Index Error when used , since the implementation is not correct.

👀 Have you spent some time to check if this issue has been raised before?

• [X] I checked and didn't find similar issue