chore: use cmp in go 1.21

Co-authored-by: H1JK <hell0jack@protonmail.com>

transport/hysteria/pmtud_fix/avail.go

@@ -1,5 +1,4 @@
-//go:build linux || windows
-// +build linux windows
+//go:build linux || windows || darwin
 
 package pmtud_fix
 

transport/hysteria/pmtud_fix/unavail.go

@@ -1,5 +1,4 @@
-//go:build !linux && !windows
-// +build !linux,!windows
+//go:build !linux && !windows && !darwin
 
 package pmtud_fix
 

transport/tuic/congestion/minmax.go

@@ -3,27 +3,11 @@ package congestion
 import (
 	"math"
 	"time"
-
-	"golang.org/x/exp/constraints"
 )
 
 // InfDuration is a duration of infinite length
 const InfDuration = time.Duration(math.MaxInt64)
 
-func Max[T constraints.Ordered](a, b T) T {
-	if a < b {
-		return b
-	}
-	return a
-}
-
-func Min[T constraints.Ordered](a, b T) T {
-	if a < b {
-		return a
-	}
-	return b
-}
-
 // MinNonZeroDuration return the minimum duration that's not zero.
 func MinNonZeroDuration(a, b time.Duration) time.Duration {
 	if a == 0 {

transport/tuic/congestion/minmax_go120.go

@@ -0,0 +1,19 @@
+//go:build !go1.21
+
+package congestion
+
+import "golang.org/x/exp/constraints"
+
+func Max[T constraints.Ordered](a, b T) T {
+	if a < b {
+		return b
+	}
+	return a
+}
+
+func Min[T constraints.Ordered](a, b T) T {
+	if a < b {
+		return a
+	}
+	return b
+}

transport/tuic/congestion/minmax_go121.go

@@ -0,0 +1,13 @@
+//go:build go1.21
+
+package congestion
+
+import "cmp"
+
+func Max[T cmp.Ordered](a, b T) T {
+	return max(a, b)
+}
+
+func Min[T cmp.Ordered](a, b T) T {
+	return min(a, b)
+}