staticcheck (#313)

* 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>

* revendor

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

* cmd,pkg: fix lint warnings

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

pkg/mesh/topology_test.go

@@ -16,7 +16,6 @@ package mesh
 
 import (
 	"net"
-	"strings"
 	"testing"
 	"time"
 
@@ -27,10 +26,6 @@ import (
 	"github.com/squat/kilo/pkg/wireguard"
 )
 
-func allowedIPs(ips ...string) string {
-	return strings.Join(ips, ", ")
-}
-
 func mustParseCIDR(s string) (r net.IPNet) {
 	if _, ip, err := net.ParseCIDR(s); err != nil {
 		panic("failed to parse CIDR")