Use new Random.Shared instead of creating new instances

tests/Jellyfin.Extensions.Tests/ShuffleExtensionsTests.cs

@@ -5,13 +5,11 @@ namespace Jellyfin.Extensions.Tests
 {
     public static class ShuffleExtensionsTests
     {
-        private static readonly Random _rng = new Random();
-
         [Fact]
         public static void Shuffle_Valid_Correct()
         {
             byte[] original = new byte[1 << 6];
-            _rng.NextBytes(original);
+            Random.Shared.NextBytes(original);
             byte[] shuffled = (byte[])original.Clone();
             shuffled.Shuffle();