add casting to prevent docs fail

Author: bombillazo

connection/connection.ts

@@ -295,7 +295,7 @@ export class Connection {
   }
 
   async #openTlsConnection(
-    connection: Deno.Conn,
+    connection: Deno.TcpConn,
     options: { hostname: string; caCerts: string[] },
   ) {
     this.#conn = await Deno.startTls(connection, options);
@@ -354,7 +354,8 @@ export class Connection {
         // https://www.postgresql.org/docs/14/protocol-flow.html#id-1.10.5.7.11
         if (accepts_tls) {
           try {
-            await this.#openTlsConnection(this.#conn, {
+            // TODO: handle connection type without casting
+            await this.#openTlsConnection(this.#conn as Deno.TcpConn, {
               hostname,
               caCerts: caCertificates,
             });