chore: add new bbr implementation

transport/tuic/congestion_v2/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
+}