Use newer version-flexible TLS/SSL method (#904)

httplib.h

@@ -6658,7 +6658,7 @@ static SSLInit sslinit_;
 inline SSLServer::SSLServer(const char *cert_path, const char *private_key_path,
                             const char *client_ca_cert_file_path,
                             const char *client_ca_cert_dir_path) {
-  ctx_ = SSL_CTX_new(SSLv23_server_method());
+  ctx_ = SSL_CTX_new(TLS_method());
 
   if (ctx_) {
     SSL_CTX_set_options(ctx_,