Update dependencies to make tests pass

[padraic-shafer]

Description

Tests are failing in GitHub CI and locally on my laptop.

Updates

• Create indexes for mongo-legacy backend
• Pin glue-core to keep glue.qglue
• Add .structure() to mongo_normalized adapters

Bonus

• Keep .env secrets out of project repo

Motivation and Context

Currently tests are failing; these changes enable test suite to pass without loss of functionality.

How Has This Been Tested?

Tested locally on MacOS (M2) with fresh instances of Mongo:(5, 6, 7) available on port 27017 (pulled from official docker hub mongo images) and with tiled image from databroker/docker-compose.yml.

[padraic-shafer]

Passes linter and unit tests in GH actions.

_NOTE: duplicate branch linked here to spur GH actions (which currently are not configured for manual workflow_dispatch)_