chore: release 1.19.1 (#562)

diff --git a/setup.py b/setup.py
index 9327cf6..52033de 100644
--- a/setup.py
+++ b/setup.py
@@ -32,7 +32,7 @@
 with io.open("README.rst", "r") as fh:
     long_description = fh.read()
 
-version = "1.19.0"
+version = "1.19.1"
 
 setup(
     name="google-auth",