update travis scripts

* bump to go 1.16
* remove unneeded part in travis/install.sh

.travis.yml

@@ -4,7 +4,7 @@ git:
   depth: 1
 env:
   - GO111MODULE=on
-go: 1.15.x
+go: 1.16.x
 os: linux
 install:
   - ./travis/install.sh

travis/install.sh

@@ -6,12 +6,3 @@ set -e
 if [[ "$TRAVIS_GO_VERSION" =~ ^1\.15\. ]]; then
     curl -sfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh| sh -s -- -b $(go env GOPATH)/bin v1.32.2
 fi
-
-# Only do this for go1.12 when modules are on so that it doesn't need to be done when modules are off as well.
-if [[ "$TRAVIS_GO_VERSION" =~ ^1\.13\. ]] && [[ "$TRAVIS_OS_NAME" == "linux" ]] && [[ "$GO111MODULE" == "on" ]]; then
-    GO111MODULE=off go get github.com/dgsb/gox
-fi
-
-if [[ "$GO111MODULE" ==  "on" ]]; then
-    go mod download
-fi