Fix: build Docker image with unshallow copy

[angela-tran]

Closes #391

[github-actions]

Coverage report

Note

Coverage data for the default branch was not found.
This usually happens when the action has not run on the default
branch yet, for example right after deploying it into the workflows.

The coverage rate is 84.98%.
The branch rate is 85%.

None of the new lines are part of the tested code. Therefore, there is no coverage data about them.

[angela-tran]

This worked!

From Azure for dev instance:

023-12-20T22:22:27.401681466Z + bin/init.sh
2023-12-20T22:22:27.462608121Z + flask init-db
2023-12-20T22:22:35.993407299Z SENTRY_DSN not set, so won't send events
2023-12-20T22:22:35.993438699Z [2023-12-20 22:22:35,993] INFO eligibility_server.app:31 Starting Eligibility Server 2023.11.1rc2.dev37+g0f1456f

[thekaveman]

@angela-tran this was a great find and fix!

I think it can be done a bit simpler directly from the actions/checkout@v4 step:

- uses: actions/checkout@v4
  with:
    # Number of commits to fetch. 0 indicates all history for all branches and tags.
    # Default: 1
    fetch-depth: 0 
    
    # Whether to fetch tags, even if fetch-depth > 0.
    # Default: false
    fetch-tags: true

Maybe the fetch-depth doesn't matter as much when we force fetch-tags, which would be even simpler!