perf: no need to decode bytes to str for json.loads

[trim21]

In a old version of python, json.loads take str only. But in python >= 3.6, it can parse bytes directly.

So there is no need to decode body to str, just feed bytes to json.loads is fine, for python>=3.8.

https://docs.python.org/3.8/library/json.html#json.loads

[trim21]

ci failed with a non relative tests

FAILED test/with_dummyserver/test_connectionpool.py::TestConnectionPoolTimeouts::test_timeout - AssertionError: timeout was pool-level SHORT_TIMEOUT rather than request-level LONG_TIMEOUT

[sigmavirus24]

Please provide performance benchmarking to justify this

[trim21]

you are right， benchmark says no such thing