Fix potential vulnerabilities due to outdated requirements

[RishabhJain2018]

There are some outdated requirements which can open potential security threats. Hence we should update the vulnerable package versions as suggested by Github. Here is the list of upgrades to be done (as suggested by Github):

1. pyyaml>=4.2b1

Please make sure to verify the validity and compatibility of suggestions with EvalAI codebase.

[krtkvrm]

Can I work on this issue?

[gautamjajoo]

@RishabhJain2018 Can I work on it?

[RishabhJain2018]

@gautamjajoo Since you are working on the other issue, let @vkartik97 work on this one :)