Azure template not working

### What is the expected behaviour?
When I click the deploy to azure button it should work.

### What is the current behaviour?
Azure opens with an error.

### How to reproduce the issue?

1. Go to [this file in your repo](https://github.com/hasura/graphql-engine/tree/stable/install-manifests/azure-container) or [this documentation page](https://hasura.io/docs/latest/graphql/core/deployment/deployment-guides/azure-container-instances-postgres.html#) (click the tab "With an existing Postgres Server").
2. Click Deploy to Azure

### Screenshots or Screencast

Start by reproducing the failure from install-manifests/azure-container or the linked Azure deployment documentation, using the “With an existing Postgres Server” tab. Inspect the Azure error shown after clicking Deploy to Azure, then update the relevant template or documentation so the deployment completes successfully and verify the button again.

Written by the indexing model from the issue text.