Fix deprecation warnings, related to use of older APIs

[sameer1001]

Not an exhaustive list, but here are some of the warnings that are coming while building the test.
https://gist.github.com/pradyunsg/0d3cfefe1f184f7c7001e85ba5ecb8be

We can take care of these by making small changes overall I guess.

I would like take this, will work on it gradually and update progress here.

[ananyo2012]

I think it will be good if you can mention the reasons that are causing the warnings and proceed with the fixes.

[sks444]

Hi @sameer1001, please note that there are two prs already fixing some of the warnings: #643, #653

Make sure the changes you're doing doesn't overlap, otherwise it will be repetitive work. :)