chore: release 1.24.0 (#656)

:robot: I have created a release \*beep\* \*boop\* 
---
## [1.24.0](https://www.github.com/googleapis/google-auth-library-python/compare/v1.23.0...v1.24.0) (2020-12-11)


### Features

* add Python 3.9 support, drop Python 3.5 support ([#655](https://www.github.com/googleapis/google-auth-library-python/issues/655)) ([6de753d](https://www.github.com/googleapis/google-auth-library-python/commit/6de753d585254c813b3e6cbde27bf5466261ba10)), closes [#654](https://www.github.com/googleapis/google-auth-library-python/issues/654)


### Bug Fixes

* avoid losing the original '_include_email' parameter in impersonated credentials ([#626](https://www.github.com/googleapis/google-auth-library-python/issues/626)) ([fd9b5b1](https://www.github.com/googleapis/google-auth-library-python/commit/fd9b5b10c80950784bd37ee56e32c505acb5078d))


### Documentation

* fix typo in import ([#651](https://www.github.com/googleapis/google-auth-library-python/issues/651)) ([3319ea8](https://www.github.com/googleapis/google-auth-library-python/commit/3319ea8ae876c73a94f51237b3bbb3f5df2aef89)), closes [#650](https://www.github.com/googleapis/google-auth-library-python/issues/650)
---


This PR was generated with [Release Please](https://github.com/googleapis/release-please).
diff --git a/setup.py b/setup.py
index 66e74ee..3006d9a 100644
--- a/setup.py
+++ b/setup.py
@@ -34,7 +34,7 @@
 with io.open("README.rst", "r") as fh:
     long_description = fh.read()
 
-version = "1.23.0"
+version = "1.24.0"
 
 setup(
     name="google-auth",