*: build with latest go versions and clean go.mod

Signed-off-by: Javi Fontan <jfontan@gmail.com>

Author: jfontan

.travis.yml

@@ -1,8 +1,8 @@
 language: go
 
 go:
-  - 1.9.x
-  - 1.10.x
+  - 1.12.x
+  - 1.13.x
 
 go_import_path: gopkg.in/src-d/go-billy.v4
 

go.mod

@@ -2,7 +2,6 @@ module gopkg.in/src-d/go-billy.v4
 
 require (
 	github.com/kr/pretty v0.1.0 // indirect
-	github.com/kr/pty v1.1.8 // indirect
 	golang.org/x/sys v0.0.0-20190726091711-fc99dfbffb4e
 	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127
 )

go.sum

@@ -1,12 +1,9 @@
-github.com/creack/pty v1.1.7/go.mod h1:lj5s0c3V2DBrqTV7llrYr5NG6My20zk30Fl46Y7DoTY=
 github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
-github.com/kr/pty v1.1.8/go.mod h1:O1sed60cT9XZ5uDucP5qwvh+TE3NnUj51EiZO/lmSfw=
 github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
-golang.org/x/sys v0.0.0-20180903190138-2b024373dcd9 h1:lkiLiLBHGoH3XnqSLUIaBsilGMUjI+Uy2Xu2JLUtTas=
-golang.org/x/sys v0.0.0-20180903190138-2b024373dcd9/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190726091711-fc99dfbffb4e h1:D5TXcfTk7xF7hvieo4QErS3qqCB4teTffacDWr7CI+0=
 golang.org/x/sys v0.0.0-20190726091711-fc99dfbffb4e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=