[#587] Do not use math/rand.Read

Fix staticcheck warnings after go1.20 update.

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

pkg/morph/client/multy_test.go

@@ -9,11 +9,11 @@ import (
 )
 
 func TestInitEndpoints(t *testing.T) {
-	rand.Seed(time.Now().UnixNano())
+	r := rand.New(rand.NewSource(time.Now().UnixNano()))
 
 	ee := make([]Endpoint, 100)
 	for i := range ee {
-		ee[i].Priority = rand.Int()
+		ee[i].Priority = r.Int()
 	}
 
 	var eeInternal endpoints