feat: Set Terraform required_version to >= 1.5

[NimJay]

• Please see this GitHub issue about requiring a minimum Terraform version between 1.3-1.5 for the "Three-tier web app" JSS (Jump Start Solution).
• We'll need to do the above for all JSSs — including this JSS.

[NimJay]

The integration test failed:

Error waiting to create function: Error waiting for Creating function: Error code 13, message: Build failed with status: INTERNAL_ERROR and message: An unexpected error occurred. Refer to build logs: https://console.cloud.google.com/cloud-build/builds;region=us-central1/3668e205-a538-4e5a-964d-b96ae3ce8835?project=741819713141. For more details see the logs at 

I don't believe it's related to the change in this pull-request. Re-running.

Aside: I believe we've been seeing this same error message in production deployments. Might be worth investigating https://console.cloud.google.com/cloud-build/builds;region=us-central1/3668e205-a538-4e5a-964d-b96ae3ce8835?project=741819713141.

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[github-actions]

This PR is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 7 days

[github-actions]

This PR is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 7 days