feat: add support for Python 3.9 / 3.10 (#220)

support for python 3.9 and 3.10 Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly: - [x] Make sure to open an issue as a [bug/issue](https://github.com/googleapis/python-iot/issues/new/choose) before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea - [ ] Ensure the tests and linter pass - [ ] Code coverage does not decrease (if any source code was changed) - [ ] Appropriate docs were updated (if necessary) Fixes #221

Author: anukaal

setup.py

@@ -67,6 +67,8 @@
  "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",
  ],