Investigate deprecation warning in Pulumi

[jhpyke]

We are currently get a warning of deprecation in Pulumi actions with latest versions of Pulumi AWS:

warning: override_json is deprecated: Use the attribute "override_policy_documents" instead.
warning: source_json is deprecated: Use the attribute "source_policy_documents" instead.

We don't call either of these directly (they are arguments for getPolicyDocument function, but we never call them directly ourselves), so the most likely villain is data-engineering-pulumi-components which also calls this function in its package, and is a requirement for this repo.

Acceptance Criteria

• The source of the deprecation warnings is identified
• A mitigation approach is agreed and implemented