Bump required aiohttp version to 3.7.4 (#2509)

Commit history before merge:

* Bump required aiohttp version to 3.7.4

This release includes an important security fix
(https://github.com/aio-libs/aiohttp/security/advisories/GHSA-v6wp-4m6f-gcjg

) and many
other improvements.

* add changelog entry
* Let's not forget about Pipfile

Co-authored-by: Richard Si <63936253+ichard26@users.noreply.github.com>