apply fix from googleapis/gapic-generator-python#2527

Author: parthea

testing/constraints-3.7.txt

@@ -5,6 +5,8 @@
 # e.g., if setup.py has "google-cloud-foo >= 1.14.0, < 2.0.0dev",
 # Then this file should have google-cloud-foo==1.14.0
 google-api-core==1.34.1
+# cryptography is a direct dependency of google-auth
+cryptography==38.0.3
 google-auth==2.14.1
 proto-plus==1.22.0
 protobuf==3.20.2