[MM-57356] Make use of go1.21 features (#26620)

server/channels/api4/user.go

@@ -8,13 +8,13 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"slices"
 	"strconv"
 	"strings"
 	"time"
 
 	"github.com/mattermost/mattermost/server/public/model"
 	"github.com/mattermost/mattermost/server/public/shared/mlog"
-	pUtils "github.com/mattermost/mattermost/server/public/utils"
 
 	"github.com/mattermost/mattermost/server/v8/channels/app"
 	"github.com/mattermost/mattermost/server/v8/channels/audit"
@@ -726,7 +726,7 @@ func getUsers(c *Context, w http.ResponseWriter, r *http.Request) {
 			c.SetInvalidParam("role")
 			return
 		}
-		roleValid := pUtils.Contains(roleNamesAll, role)
+		roleValid := slices.Contains(roleNamesAll, role)
 		if !roleValid {
 			c.SetInvalidParam("role")
 			return