Bump aiohttp from 3.7.1 to 3.7.4

Bumps [aiohttp](https://github.com/aio-libs/aiohttp) from 3.7.1 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@v3.7.1...v3.7.4)

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

homeassistant/package_constraints.txt

@@ -1,6 +1,6 @@
 PyJWT==1.7.1
 PyNaCl==1.3.0
-aiohttp==3.7.1
+aiohttp==3.7.4
 aiohttp_cors==0.7.0
 astral==1.10.1
 async_timeout==3.0.1

requirements.txt

@@ -1,7 +1,7 @@
 -c homeassistant/package_constraints.txt
 
 # Home Assistant Core
-aiohttp==3.7.1
+aiohttp==3.7.4
 astral==1.10.1
 async_timeout==3.0.1
 attrs==19.3.0