Restore original aiohttp cancelation behavior

[bdraco]

Proposed change

aiohttp will now preserve the 3.8.1 handler cancellation on disconnect behavior which is now the unreleased 3.9.x version behavior of setting handler_cancellation to True (docs: aio-libs/aiohttp#7128)

This shim can be removed when 3.9.x is released and replaced with setting handler_cancellation to True

#88032 (comment)

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
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• Breaking change (fix/feature causing existing functionality to break)
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