[AIRFLOW-5089] Spanner compatibility bug causes missing imports

[potiuk]

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[ashb]

The issue is I think that clous-spanner 1.10.0 now needs https://pypi.org/project/google-cloud-iam/#history 0.2.0 but didn't list that as a dep.

[potiuk]

Yeah. Let's fix it for now to unblock master merges and we will have a separate work on aligning all gcp dependencies.

[ashb]

I was slightly wrong, but its related to this:

google-cloud-container 0.3.0 has requirement grpc-google-iam-v1<0.13dev,>=0.12.3, but you'll have grpc-google-iam-v1 0.11.4 which is incompatible.
google-cloud-spanner 1.10.0 has requirement grpc-google-iam-v1<0.13dev,>=0.12.3, but you'll have grpc-google-iam-v1 0.11.4 which is incompatible.