new cachetools version (5.0.0+) can't work with google-auth #934

cachetools has released a new version (5.0.0) which conflicts with google-auth requirements of it being <5, this prevents updates to the cachetools package and pose a potential security concern (as updates are no longer possible to it)

The conflict is caused by:
    The user requested cachetools==5.0.0
    google-auth 2.3.3 depends on cachetools<5.0 and >=2.0.0

issue seems in

Environment details

• OS: alpine3.11
• Python version: python:3.8.6
• pip version: 20.3.3
• google-auth version: 2.3.3 (latest at time of writing)

Steps to reproduce

1. try pip install using latest cachetools with latest google-auth
2. pip fails