refactor: remove unused option

This option was added by error during the TypeScript migration.

Related: 587ccf3

Author: darrachequesne

lib/socket.ts

@@ -82,12 +82,6 @@ export interface SocketOptions {
    */
   transports: string[];
 
-  /**
-   * The port the policy server listens on
-   * @default 843
-   */
-  policyPost: number;
-
   /**
    * If true and if the previous websocket connection to the server succeeded,
    * the connection attempt will bypass the normal upgrade process and will