feat: rand seed compatible with >=go1.20

rand.go

@@ -5,9 +5,10 @@ import (
 	"time"
 )
 
-func init() {
-	rand.Seed(time.Now().UnixNano())
-}
+var (
+	source = rand.NewSource(time.Now().UnixNano())
+	random = rand.New(source)
+)
 
 // standard characters used by uniuri
 const letterBytes = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
@@ -16,7 +17,7 @@ const letterBytes = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456
 func RandomString(n int) string {
 	b := make([]byte, n)
 	for i := range b {
-		b[i] = letterBytes[rand.Intn(len(letterBytes))]
+		b[i] = letterBytes[random.Intn(len(letterBytes))]
 	}
 	return string(b)
 }