CI: use staticcheck for linting

This commit switches the linter for Go code from golint to staticcheck.
Golint has been deprecated since last year and staticcheck is a
recommended replacement.

Signed-off-by: Lucas Servén Marín <lserven@gmail.com>

tools.go

@@ -19,7 +19,7 @@ package main
 
 import (
 	_ "github.com/campoy/embedmd"
-	_ "golang.org/x/lint/golint"
+	_ "honnef.co/go/tools/cmd/staticcheck"
 	_ "k8s.io/code-generator/cmd/client-gen"
 	_ "k8s.io/code-generator/cmd/deepcopy-gen"
 	_ "k8s.io/code-generator/cmd/informer-gen"