THRIFT-5876: Add Delphi WinHTTP client TLS1.3 support
Client: Delphi
Patch: fcprete & Jens Geyer

This closes #3166
diff --git a/lib/delphi/src/Thrift.Transport.WinHTTP.pas b/lib/delphi/src/Thrift.Transport.WinHTTP.pas
index 2d18ca1..5a6f213 100644
--- a/lib/delphi/src/Thrift.Transport.WinHTTP.pas
+++ b/lib/delphi/src/Thrift.Transport.WinHTTP.pas
@@ -192,7 +192,8 @@
     WINHTTP_FLAG_SECURE_PROTOCOL_SSL3,
     WINHTTP_FLAG_SECURE_PROTOCOL_TLS1,
     WINHTTP_FLAG_SECURE_PROTOCOL_TLS1_1,
-    WINHTTP_FLAG_SECURE_PROTOCOL_TLS1_2
+    WINHTTP_FLAG_SECURE_PROTOCOL_TLS1_2,
+    WINHTTP_FLAG_SECURE_PROTOCOL_TLS1_3
   );
 var
   prot : TSecureProtocol;