Travis: update shfmt to 1.3.1 (#2949)
Travis: update shfmt to 1.3.1 (#2949)


Frenzie/koreader,mwoz123/koreader,robert00s/koreader,apletnev/koreader,lgeek/koreader,koreader/koreader,NiLuJe/koreader,poire-z/koreader,koreader/koreader,Hzj-jie/koreader,mihailim/koreader,poire-z/koreader,NiLuJe/koreader,Markismus/koreader,Frenzie/koreader,pazos/koreader,houqp/koreader