Add CODE_OF_CONDUCT file

[Susmita-Dey]

Is your feature request related to a problem? Please describe.
CODE_OF_CONDUCT file is missing in this repository. This is an important file that should be present in a repository.

Describe the solution you'd like
I want to add the CODE_OF_CONDUCT file.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.

Do you want to work on this issue - [Yes/No]

Yes
I'm a GSSoC'22 contributor. Kindly assign this to me.