feat: add support for python 3.10 (#274)

Author: parthea

google-cloud-speech/setup.py

@@ -80,6 +80,8 @@
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
+        "Programming Language :: Python :: 3.10",
         "Operating System :: OS Independent",
         "Topic :: Internet",
     ],