Bump aiohttp from 3.6.2 to 3.7.4 in /cirrus-ci_artifacts

Bumps [aiohttp](https://github.com/aio-libs/aiohttp) from 3.6.2 to 3.7.4.
- [Release notes](https://github.com/aio-libs/aiohttp/releases)
- [Changelog](https://github.com/aio-libs/aiohttp/blob/master/CHANGES.rst)
- [Commits](aio-libs/aiohttp@v3.6.2...v3.7.4)

Signed-off-by: dependabot[bot] <support@github.com>

cirrus-ci_artifacts/requirements.txt

@@ -1,4 +1,4 @@
-aiohttp==3.6.2
+aiohttp==3.7.4
 async-timeout==3.0.1
 attrs==20.2.0
 certifi==2020.6.20