language: go

go:
  - 1.13
  - stable

language: go

env:
  - GO111MODULE=on

go:
  - 1.11
  - 1.12
  - 1.13
  - stable

Drop go < 1.11 CI support due to go modules
Drop go < 1.11 CI support due to go modules

and update build go version matrix.
