Travis updates

- Add Go 1.17
- Fix go fmt from Go 1.17 (build directives)
- Download version of misspell and staticcheck instead of doing
"go get" since current staticcheck would be broken without go.mod

Signed-off-by: Ivan Kozlovic <ivan@synadia.com>

.travis.yml

@@ -7,8 +7,8 @@ vm:
 
 language: go
 go:
+- 1.17.x
 - 1.16.x
-- 1.15.x
 addons:
   apt:
     packages:
@@ -17,11 +17,8 @@ env:
 - GO111MODULE=off
 go_import_path: github.com/nats-io/nats-server
 install:
-- go get github.com/nats-io/nats.go/
-- go get github.com/nats-io/nkeys
-- go get github.com/nats-io/jwt
-- go get -u honnef.co/go/tools/cmd/staticcheck
-- go get -u github.com/client9/misspell/cmd/misspell
+- GO111MODULE=on go get honnef.co/go/tools/cmd/staticcheck@2021.1.2
+- GO111MODULE=on go get github.com/client9/misspell/cmd/misspell@v0.3.4
 before_script:
 - GO_LIST=$(go list ./...)
 - go build
@@ -33,10 +30,10 @@ script:
 - set -e
 - if [[ $TRAVIS_TAG ]]; then go test -v -run=TestVersionMatchesTag ./server; fi
 - if [[ ! $TRAVIS_TAG ]]; then go test -v -run=TestNoRace --failfast -p=1 -timeout 20m ./...; fi
-- if [[ ! $TRAVIS_TAG ]]; then if [[ "$TRAVIS_GO_VERSION" =~ 1.15 ]]; then ./scripts/cov.sh TRAVIS; else go test -v -race -p=1 --failfast -timeout 20m ./...; fi; fi
+- if [[ ! $TRAVIS_TAG ]]; then if [[ "$TRAVIS_GO_VERSION" =~ 1.16 ]]; then ./scripts/cov.sh TRAVIS; else go test -v -race -p=1 --failfast -timeout 20m ./...; fi; fi
 - set +e
 after_success:
-- if [[ ! $TRAVIS_TAG ]]; then if [[ "$TRAVIS_GO_VERSION" =~ 1.15 ]]; then $HOME/gopath/bin/goveralls -coverprofile=acc.out -service travis-ci; fi; fi
+- if [[ ! $TRAVIS_TAG ]]; then if [[ "$TRAVIS_GO_VERSION" =~ 1.16 ]]; then $HOME/gopath/bin/goveralls -coverprofile=acc.out -service travis-ci; fi; fi
 
 deploy:
   provider: script