support tts deepgram (#277)

lib/utils/speech-utils.js

@@ -233,6 +233,24 @@ const testWhisper = async(logger, synthAudio, credentials) => {
   }
 };
 
+const testDeepgramTTS = async(logger, synthAudio, credentials) => {
+  try {
+    await synthAudio({increment: () => {}, histogram: () => {}},
+      {
+        vendor: 'deepgram',
+        credentials,
+        language: 'en-US',
+        voice: 'alpha-aurora-en-v2',
+        model: 'alpha-aurora-en-v2',
+        text: 'Hi there and welcome to jambones!'
+      }
+    );
+  } catch (err) {
+    logger.info({err}, 'testDeepgramTTS returned error');
+    throw err;
+  }
+};
+
 const testIbmTts = async(logger, getTtsVoices, credentials) => {
   const {tts_api_key, tts_region} = credentials;
   const voices = await getTtsVoices({vendor: 'ibm', credentials: {tts_api_key, tts_region}});
@@ -418,6 +436,7 @@ module.exports = {
   testSonioxStt,
   testElevenlabs,
   testAssemblyStt,
+  testDeepgramTTS,
   getSpeechCredential,
   decryptCredential,
   testWhisper