use slices.Contains from go1.21

irc/chanserv.go

 import (
 	"fmt"
 	"regexp"
+	"slices"
 	"sort"
 	"strings"
 	"time"
 	// check for anything valid as a channel mode change that is not valid
 	// as an AMODE change
 	for _, modeChange := range modeChanges {
-		if !utils.SliceContains(modes.ChannelUserModes, modeChange.Mode) {
+		if !slices.Contains(modes.ChannelUserModes, modeChange.Mode) {
 			invalid = true
 		}
 	}

irc/utils/types.go

 	}
 	return
 }
-
-func SliceContains[T comparable](slice []T, elem T) (result bool) {
-	for _, t := range slice {
-		if elem == t {
-			return true
-		}
-	}
-	return false
-}