aiodns tests fail because "example.com" gives different IP address on each query

Hi. Title pretty much describes issue.
Couldnt build latest (0.21) uvloop rpm because dns test failed because of IP addresses not match. example.com seems ot be behind CDN, thus there are a lot of IP addresses.
Workaround for me was just add "example.com" entry into hosts, but i decided i should probably create issue on github too.