chore(deps): update dependency botocore to v1.23.21 (GoogleCloudPlatform#7202)

Co-authored-by: Leah E. Cole <[email protected]>

Author: renovate-bot

iam/api-client/requirements.txt

@@ -2,4 +2,4 @@ google-api-python-client==2.33.0
 google-auth==2.3.3
 google-auth-httplib2==0.1.0
 boto3==1.20.20
-botocore==1.23.20
+botocore==1.23.21