add constraints for 3.8

Author: ohmayr

testing/constraints-3.8.txt

@@ -1,2 +1,14 @@
+# This constraints file is used to check that lower bounds
+# are correct in setup.py
+# List *all* library dependencies and extras in this file.
+# Pin the version to the lower bound.
+#
+# e.g., if setup.py has "foo >= 1.14.0, < 2.0.0dev",
+# Then this file should have foo==1.14.0
 googleapis-common-protos==1.63.2
-protobuf==4.25.8
+protobuf==4.25.8
+google-auth==2.14.1
+requests==2.18.0
+grpcio==1.33.2
+grpcio-status==1.33.2
+proto-plus==1.22.3