chore(deps): update dependency google-cloud-spanner to v3.35.1 (#952)

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

Author: renovate-bot

samples/samples/requirements.txt

@@ -1,2 +1,2 @@
-google-cloud-spanner==3.33.0
+google-cloud-spanner==3.35.1
 futures==3.4.0; python_version < "3"