chore(deps): update dependency google-cloud-spanner to v3.33.0 (#933)

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

Author: 3 people

samples/samples/requirements.txt

@@ -1,2 +1,2 @@
-google-cloud-spanner==3.31.0
+google-cloud-spanner==3.33.0
 futures==3.4.0; python_version < "3"