Bump spec target to 0.17
Bump spec target to 0.17

postalservice14/commonmark,fesor/commonmark,thephpleague/commonmark,colinodell/commonmark,stof/commonmark,kkiernan/commonmark,bcremer/commonmark,hason/commonmark,postalservice14/commonmark,fesor/commonmark,garethellis36/commonmark,garethellis36/commonmark,hason/commonmark,kkiernan/commonmark,thephpleague/commonmark