add whisper to backend

I should do the testing on colab, but testing is easy here because of microphone option i believe

backend/audio_to_tgt.py

@@ -1,2 +1,6 @@
 def src_audio_to_eng_translator(audio_file_input):
-    return "Random"
+    transcription = client.audio.translations.create(
+    model="whisper-1", 
+    file=audio_file_input,
+    )
+    return transcription.text