Bump aiohttp from 3.6.3 to 3.7.2 (#383)

Bumps [aiohttp](https://github.com/aio-libs/aiohttp) from 3.6.3 to 3.7.2.
- [Release notes](https://github.com/aio-libs/aiohttp/releases)
- [Changelog](https://github.com/aio-libs/aiohttp/blob/master/CHANGES.rst)
- [Commits](aio-libs/aiohttp@v3.6.3...v3.7.2)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

requirements-dev.txt

@@ -3,7 +3,7 @@ flake8==3.8.4
 coverage==5.3
 sphinx==3.2.1
 alabaster>=0.6.2
-aiohttp==3.6.3
+aiohttp==3.7.2
 jinja2==2.11.2
 pytest==6.1.2
 pytest-cov==2.10.1