Added "308 Permanent Redirect" to ReasonPhrases

From RFC7538 - https://tools.ietf.org/html/rfc7538

Author: khellang

src/Microsoft.AspNetCore.Server.Kestrel/Internal/Http/ReasonPhrases.cs

@@ -28,6 +28,7 @@ public static class ReasonPhrases
         private static readonly byte[] _bytesStatus305 = Encoding.ASCII.GetBytes("305 Use Proxy");
         private static readonly byte[] _bytesStatus306 = Encoding.ASCII.GetBytes("306 Reserved");
         private static readonly byte[] _bytesStatus307 = Encoding.ASCII.GetBytes("307 Temporary Redirect");
+        private static readonly byte[] _bytesStatus308 = Encoding.ASCII.GetBytes("308 Permanent Redirect");
         private static readonly byte[] _bytesStatus400 = Encoding.ASCII.GetBytes("400 Bad Request");
         private static readonly byte[] _bytesStatus401 = Encoding.ASCII.GetBytes("401 Unauthorized");
         private static readonly byte[] _bytesStatus402 = Encoding.ASCII.GetBytes("402 Payment Required");
@@ -107,6 +108,8 @@ public static byte[] ToStatusBytes(int statusCode, string reasonPhrase = null)
                         return _bytesStatus306;
                     case 307:
                         return _bytesStatus307;
+                    case 308:
+                        return _bytesStatus308;
                     case 400:
                         return _bytesStatus400;
                     case 401:
@@ -178,4 +181,4 @@ public static byte[] ToStatusBytes(int statusCode, string reasonPhrase = null)
             return Encoding.ASCII.GetBytes(statusCode.ToString(CultureInfo.InvariantCulture) + " " + reasonPhrase);
         }
     }
-}
+}