Creating 'dev' deployment, branch, and Cloud Run instance

[EddieLF]

We should create a development environment to test changes before merging them into production / main.

• [x] Create a new branch called dev
• [ ] Create a new Cloud Run instance called curator-dev. In the Cloud Run template spec, ideally we would have ALLOWED_HOSTS = curator-dev.<url>
• [ ] Create or update GitHub deploy workflow for the dev branch. Uncomment this line, and add/update the if conditions in the workflow yaml to if: github.ref == 'refs/heads/main' || 'refs/heads/dev' for the docker build and docker push steps. The set deployment info step seems to cover most of the other steps for deploying dev changes.
• [ ] Adjust any other settings for the dev environment, e.g. Django credentials, enabling debug mode, secret key. Not sure what might be required or recommended here.

[EddieLF]

Closing this as local dev environments have shown to be supported, meaning there is currently no need for a dedicated dev instance.