Requests-doh

Fix bugs

- Fixed missing dependencies (`ModuleNotFoundError: No module named socks`)

Fix bugs
- Fixed requests with socks proxy is not working 3

Note: Potential breaking changes

Functions `set_dns_cache_expire_time()` and `purge_dns_cache()` imported from module `requests_doh.connector` are no longer exists. Instead you can import it from `requests_doh.cachemanager`

If you usually import those functions from `requests_doh` (root library), these changes doesn't affect you at all.

For example:

python
If you do this starting from v0.3.2, you will get `ImportError`
from requests_doh.connector import set_dns_cache_expire_time, purge_dns_cache

Do this instead
from requests_doh.cachemanager import set_dns_cache_expire_time, purge_dns_cache

Those changes doesn't affect you if you use this import method
from requests_doh import set_dns_cache_expire_time, purge_dns_cache

This update fix `requests` dependencies because of [CVE-202-32681](https://github.com/psf/requests/security/advisories/GHSA-j8r2-6x86-q33q)

Dependencies

- Bump requests from v2.28.2 to v2.31.0

New features

- Added ability to add custom DNS over HTTPS provider [1](https://github.com/mansuf/requests-doh/issues/1)
- Added ability to remove DNS over HTTPS provider

Improvements

- Improved performance for querying DNS over HTTPS

Dependecies

- Updated requests from v2.28.1 to v2.28.2
- Updated dnspython from v2.2.1 to v2.3.0

Fix bugs

- Fixed missing dependecies resulting error `dns.query.NoDOH: Neither httpx nor requests is available.`