Adds missing type

Signed-off-by: Bandini Bhopi <bandinib@amazon.com>

lib/Transport.d.ts

@@ -30,7 +30,7 @@
 import { Readable as ReadableStream } from 'stream';
 import Connection from './Connection';
 import * as errors from './errors';
-import { CloudConnectionPool, ConnectionPool } from './pool';
+import { CloudConnectionPool, ConnectionPool, BasicAuth, AwsSigv4Auth } from './pool';
 import Serializer from './Serializer';
 
 export type ApiError =