fix compilation with older version; readMaybe doesn't exist on < 7.6
fix compilation with older version; readMaybe doesn't exist on < 7.6

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