Replace deprecated math/rand functions (#30733)

Suggested by logs in #30729

- Remove `math/rand.Seed`
`rand.Seed is deprecated: As of Go 1.20 there is no reason to call Seed
with a random value.`
- Replace `math/rand.Read`
`rand.Read is deprecated: For almost all use cases, [crypto/rand.Read]
is more appropriate.`
- Replace `math/rand` with `math/rand/v2`, which is available since Go
1.22

models/user/user_test.go

@@ -5,8 +5,8 @@ package user_test
 
 import (
 	"context"
+	"crypto/rand"
 	"fmt"
-	"math/rand"
 	"strings"
 	"testing"
 	"time"