Limit dnspython to version 2.0.0+ (https://github.com/rthalley/dnspython/pull/503), otherwise the test fails with: E AttributeError: module 'dns.edns' has no attribute 'OptionType'
Limit dnspython to version 2.0.0+ (https://github.com/rthalley/dnspython/pull/503), otherwise the test fails with: E AttributeError: module 'dns.edns' has no attribute 'OptionType'