What problem do you want to solve?

Currently, aiohttp-client doesn't make available http.response.body.size. This is a very useful span attribute and would be great to have for both unchunked and chunked responses.

Describe the solution you'd like

http.response.body.size populated in the span and metrics provided

Describe alternatives you've considered

No response

Additional Context

No response

Would you like to implement a fix?

None