travis: update test matrix
MODIFY
.travis.yml
.travis.yml
@@ -5,9 +5,9 @@ language: go
# Do not move these lines; they are referred to by README.md.
# Versions of go that are explicitly supported by gonum plus go tip.
go:
+ - 1.12.x
- 1.11.x
- 1.10.x
- - 1.9.x
- master
env:

travis: update test matrix