Bump aiohttp from 3.7.2 to 3.7.3

Bumps [aiohttp](https://github.com/aio-libs/aiohttp) from 3.7.2 to 3.7.3.
- [Release notes](https://github.com/aio-libs/aiohttp/releases)
- [Changelog](https://github.com/aio-libs/aiohttp/blob/master/CHANGES.rst)
- [Commits](https://github.com/aio-libs/aiohttp/compare/v3.7.2...v3.7.3)

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

requirements.txt

@@ -2,7 +2,7 @@ numpy==1.19.4
 pandas==1.1.4
 
 ccxt==1.38.13
-aiohttp==3.7.2
+aiohttp==3.7.3
 SQLAlchemy==1.3.20
 python-telegram-bot==13.0
 arrow==0.17.0