Remove dep from Travis CI

Was missed from previous switch to go modules

.travis.yml

@@ -3,9 +3,6 @@ go:
   - 1.12.x
 install:
   # Fetch dependencies
-  - wget -O dep https://github.com/golang/dep/releases/download/v0.5.0/dep-linux-amd64
-  - chmod +x dep
-  - mv dep $GOPATH/bin/dep
   - curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh -s -- -b $GOPATH/bin v1.17.1
 script:
   - ./configure && make test