Avoid using network at import time

The latest version of msal can open sockets at import time as part of DNS resolution
This is from https://github.com/AzureAD/microsoft-authentication-library-for-python/commit/95ccef07ca9f806ab51e9a04e40826c9c8e897bb#diff-24c0727ff4626c6c535d05c13b61fa4b4a47d6fc4496ec0ceadc734191de19cbR128
cc @rayluo 