chore(deps): update dependency google-auth to v2.15.0 (#318)

Co-authored-by: Anthonios Partheniou <[email protected]>

Author: renovate-bot

privateca/snippets/requirements-test.txt

@@ -1,3 +1,3 @@
 pytest==7.2.0
-google-auth==2.14.1
+google-auth==2.15.0
 cryptography==38.0.4