fix: use correct syntax for initializing the token manager (#220)

This method of initializing the token manager is no longer supported, as its not consistent with all of the other services in the Node SDK. This update will ensure that that Line 35 does not break the code.

app.js

@@ -32,7 +32,7 @@ const serviceUrl = process.env.SPEECH_TO_TEXT_URL || 'https://stream.watsonplatf
 
 if (process.env.SPEECH_TO_TEXT_IAM_APIKEY && process.env.SPEECH_TO_TEXT_IAM_APIKEY !== '') {
   instanceType = 'iam';
-  tokenManager = new IamTokenManagerV1.IamTokenManagerV1({
+  tokenManager = new IamTokenManagerV1({
     iamApikey: process.env.SPEECH_TO_TEXT_IAM_APIKEY || '<iam_apikey>',
     iamUrl: process.env.SPEECH_TO_TEXT_IAM_URL || 'https://iam.bluemix.net/identity/token',
   });