Bump multidict from 4.7.3 to 4.7.4

Bumps [multidict](https://github.com/aio-libs/multidict) from 4.7.3 to 4.7.4.
- [Release notes](https://github.com/aio-libs/multidict/releases)
- [Changelog](https://github.com/aio-libs/multidict/blob/master/CHANGES.rst)
- [Commits](aio-libs/multidict@v4.7.3...v4.7.4)

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

Author: dependabot-preview[bot]

requirements.txt

@@ -13,7 +13,7 @@ cffi==1.13.2              # via pycares
 chardet==3.0.4            # via aiohttp
 fonttools==4.2.4
 idna==2.8                 # via yarl
-multidict==4.7.3          # via aiohttp, yarl
+multidict==4.7.4          # via aiohttp, yarl
 pycares==3.1.0            # via aiodns
 pycparser==2.19           # via cffi
 yarl==1.4.2               # via aiohttp