Use `httpx` instead of `requests` for async compatibility

[YoussefHenna]

Closes https://github.com/logdna/python/issues

The project is outdated and as such I'm getting linting and installation errors, however I have been able to integrate this into my project successfully and can confirm it works with a FastAPI server. If someone is willing to fix up linting and poetry-related issues, this should be good to go.