Integration with oss-fuzz fuzzing service

[manunio]

Hi, I would like to help integrate this project into OSS-Fuzz. Additionally projects like aiohttp, requests has also been integrated into oss-fuzz.

• As an initial step for integration I have created this PR: httpx: initial integration google/oss-fuzz#8505, it contains necessary logic from an OSS-Fuzz perspective to integrate HTTPX, This includes developing initial fuzzers as well as integrating into OSS-Fuzz.

• OSS-Fuzz is a free service run by Google that performs continuous fuzzing of important open source projects.

• Essentially, Fuzzing is a way to automate test-case generation and can be used to find unexpected exceptions in Python.

• If you would like to integrate, the only thing I need is a list of email(s), it must be associated with a google account like gmail (why?). by doing that, the provided email(s) will get access to the data produced by OSS-Fuzz, such as bug reports, coverage reports and more stats.

• As an alternative, if you don't have a gmail id or you don't wish to provide your email, but still wish to integrate. I can add my mail id for time being and monitor bug/crashes.

• Notice the email(s) affiliated with the project will be public in the OSS-Fuzz repo, as they will be part of a configuration file.