fix: add google-auth as a direct dependency

chore: remove deprecated constraints-3.7.txt file

Fixes #3274

PiperOrigin-RevId: 604992877

Author: vertex-sdk-bot

setup.py

@@ -173,6 +173,7 @@
     include_package_data=True,
     install_requires=(
         "google-api-core[grpc] >= 1.32.0, <3.0.0dev,!=2.0.*,!=2.1.*,!=2.2.*,!=2.3.*,!=2.4.*,!=2.5.*,!=2.6.*,!=2.7.*",
+        "google-auth >= 2.14.1, <3.0.0dev",
         "proto-plus >= 1.22.0, <2.0.0dev",
         "protobuf>=3.19.5,<5.0.0dev,!=3.20.0,!=3.20.1,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
         "packaging >= 14.3",

testing/constraints-3.7.txt

@@ -1,7 +1,9 @@
 # -*- coding: utf-8 -*-
-# This constraints file is required for unit tests.
-# List all library dependencies and extras in this file.
+# This constraints file is used to check that lower bounds
+# are correct in setup.py
+# List *all* library dependencies and extras in this file.
 google-api-core
+google-auth==2.14.1
 proto-plus==1.22.0
 protobuf
 mock==4.0.2