According to [ansible lifecyle], the ansible 2.8 is security fixes
And ansible 2.8 already breaks our CI on Fedora 32 when
trying to collect service facts:
Meanwhile, due to lacking of support relative import, the files
in `modules_utils` are required to use:
from ansible.module_utils.xxx.error import LsrNetworkNmError
from .error import LsrNetworkNmError
Lacking of relative import also requires a lot hack to our unit tests.
Hence I would like to suggest we drop the support of ansible 2.8.