Upgrade aiohttp to 3.7.4.post0

[frenck]

Proposed change

Upgrades aiohttp to 3.7.4.post0, which bumps upper bound of the chardet runtime dependency.

Changelog: https://docs.aiohttp.org/en/stable/changes.html#post0-2021-03-06
Addresses: aio-libs/aiohttp#5366

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
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