Set Docker healthcheck in the Dockerfile

[ColinHebert]

Proposed change

Set the docker healthcheck in the docker image, so any user benefits from it out of the box without having to rely on extra configuration.

Closes #(issue or discussion)

Type of change

• Bug fix: non-breaking change which fixes an issue.
• New feature: non-breaking change which adds functionality. Please read the important note above.
• Breaking change: fix or feature that would cause existing functionality to not work as expected.
• Documentation only.
• Other. Please explain:

Checklist:

• I have read & agree with the contributing guidelines.
• If applicable, I have included testing coverage for new code in this PR, for backend and / or front-end changes.
• If applicable, I have tested my code for new features & regressions on both mobile & desktop devices, using the latest version of major browsers.
• If applicable, I have checked that all tests pass, see documentation.
• I have run all pre-commit hooks, see documentation.
• I have made corresponding changes to the documentation as needed.
• I have checked my modifications for any breaking changes.

[paperless-ngx-secretary]

Hello @ColinHebert,

thank you very much for submitting this PR to us!

This is what will happen next:

1. My robotic colleagues will check your changes to see if they break anything. You can see the progress below.
2. Once that is finished, human contributors from paperless-ngx review your changes. Since this seems to be a small change, only a single contributor has to review your changes.
3. Please improve anything that comes up during the review until your pull request gets approved.
4. Your pull request will be merged into the dev branch. Changes there will be tested further.
5. Eventually, changes from you and other contributors will be merged into main and a new release will be made.

Please allow up to 7 days for an initial review. We're all very excited about new pull requests but we only do this as a hobby.
If any action will be required by you, please reply within a month.

[ColinHebert]

Note, this pull requests simply adds the new healthcheck.
To not confuse the users, the healthcheck currently added to the docker-compose files should be kept in the compose files until a new stable version of the paperless-ngx docker image is published.

I have a pull request ready to go when this is the case. This said, even the docker-compose change is optional (though it will make it more convenient if in the future changes need to be made to the healtcheck across the board.

[stumpylog]

I can't find any reason this was only in the compose files before, looks good to me

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new discussion or issue for related concerns.