bump certificate version to 0.7 minimum
bump certificate version to 0.7 minimum

erikd/hs-tls,tolysz/hs-tls,AaronFriel/hs-tls,AaronFriel/hs-tls,beni55/hs-tls,erikd/hs-tls,tolysz/hs-tls,lancelotsix/hs-tls,beni55/hs-tls,lancelotsix/hs-tls