Bump google-auth from 2.16.2 to 2.16.3 in /tests

Bumps [google-auth](https://github.com/googleapis/google-auth-library-python) from 2.16.2 to 2.16.3.
- [Release notes](https://github.com/googleapis/google-auth-library-python/releases)
- [Changelog](https://github.com/googleapis/google-auth-library-python/blob/main/CHANGELOG.md)
- [Commits](googleapis/google-auth-library-python@v2.16.2...v2.16.3)

---
updated-dependencies:
- dependency-name: google-auth
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

tests/requirements.txt

@@ -204,9 +204,9 @@ flaky==3.7.0 \
 forcediphttpsadapter==1.0.2 \
     --hash=sha256:f7582b34aaa6ab6b17f69ab1abbfe67097b952ed0682b758b5e01e18fe24433e
     # via -r requirements.txt
-google-auth==2.16.2 \
-    --hash=sha256:07e14f34ec288e3f33e00e2e3cc40c8942aa5d4ceac06256a28cd8e786591420 \
-    --hash=sha256:2fef3cf94876d1a0e204afece58bb4d83fb57228aaa366c64045039fda6770a2
+google-auth==2.16.3 \
+    --hash=sha256:4dfcfd8ecd1cf03ddc97fddfb3b1f2973ea4f3f664aa0d8cfaf582ef9f0c60e7 \
+    --hash=sha256:611779ce33a3aee265b94b74d4bb8c188f33010f5814761250a0ebbde94cc745
     # via
     #   -r requirements.txt
     #   kubernetes