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

Author: parthea

testing/constraints-3.7.txt

@@ -7,6 +7,8 @@
 # Then this file should have foo==1.14.0
 google-api-core==1.34.0
 google-auth==2.14.1
+# cryptography is a direct dependency of google-auth
+cryptography==38.0.3
 google-cloud-core==1.4.0
 proto-plus==1.22.0
 libcst==0.2.5