Description of problem:
The current EPEL 8 python3-httpcore package has dependencies that are not specified.

https://github.com/encode/httpcore/blob/0.12.2/setup.py#L56

This prevents importing of the Python module.


Version-Release number of selected component (if applicable):
python3-httpcore-0.12.2-1.el8


How reproducible:
always


Steps to Reproduce:
1. dnf install python3 python3-httpcore
2. python3 -c 'import httpcore'


Actual results:
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python3.6/site-packages/httpcore/__init__.py", line 2, in <module>
    from ._async.connection_pool import AsyncConnectionPool
  File "/usr/lib/python3.6/site-packages/httpcore/_async/connection_pool.py", line 15, in <module>
    from .._backends.auto import AsyncBackend, AsyncLock, AsyncSemaphore
  File "/usr/lib/python3.6/site-packages/httpcore/_backends/auto.py", line 4, in <module>
    import sniffio
ModuleNotFoundError: No module named 'sniffio'


Expected results:
successful import