feat(v2beta1): Add ability to set Cloud Speech model in SpeechToTextConfig (#587)

* feat: Can directly set Cloud Speech model on the SpeechToTextConfig

PiperOrigin-RevId: 482665674

Source-Link: googleapis/googleapis@64926d5

Source-Link: googleapis/googleapis-gen@351722b
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiMzUxNzIyYmUxNjNkZWY3NjY2ZjEzY2I3NmIyYTI5NWQ5ZjJhODQ1MCJ9

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: gcf-owl-bot[bot]

packages/google-cloud-dialogflow/google/cloud/dialogflow_v2beta1/types/audio_config.py

@@ -501,13 +501,24 @@ class SpeechToTextConfig(proto.Message):
             request. If enhanced model variant is specified and an
             enhanced version of the specified model for the language
             does not exist, then it would emit an error.
+        model (str):
+            Which Speech model to select. Select the model best suited
+            to your domain to get best results. If a model is not
+            explicitly specified, then a default model is used. Refer to
+            `Cloud Speech API
+            documentation <https://cloud.google.com/speech-to-text/docs/basics#select-model>`__
+            for more details.
     """
 
     speech_model_variant = proto.Field(
         proto.ENUM,
         number=1,
         enum="SpeechModelVariant",
     )
+    model = proto.Field(
+        proto.STRING,
+        number=2,
+    )
 
 
 __all__ = tuple(sorted(__protobuf__.manifest))