Added GitHub workflow for tests in Postgres

[marcusmoore]

Description

This PR adds a GitHub workflow to run the test suite in Postgres. (Keeping in mind Postgres is not officially supported)

Unlike our existing testing Actions that run on PR opening, commits to open PRs, or merges to develop and master I set this one to run when manually triggered. This because I don't want our PR and commits lists to be full of ❌s in addition to flooding author notifications due to failing tests due to an unsupported database.

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Until the artifacts are purged, the tests are are failing in are viewable here.

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Type of change

• Chore

[what-the-diff]

PR Summary

• Introduction of a New Automated Testing Process
  We have added a new file called '.github/workflows/tests-postgres.yml'. It establishes a standardized testing procedure for our code, checking its compatibility with the Postgres database.

• Applicable Triggers
  The new testing process will run after changes are made and committed to the master and develop branches. It will also trigger in response to newly submitted pull requests.

• Environment and Tools Used
  The automated tests are designed to operate on the most recent Ubuntu operating system. They connect to a Postgres service container for database interaction and utilize PHP version 8.2.

• Test Workflow Steps
  The steps involve setting up PHP, integrating the code in the project, caching Composer dependencies, arranging .env files, installing dependencies, configuring Laravel, and carrying out tests with PHPUnit.

• Database Connection Information
  The necessary setup details for connecting to the Postgres database are specified within the test steps.