Fix warnings

[anolpe]

WHY:

Advances #559

What has been changed (if possible, add screenshots, gifs, etc. )

version has been removed from docker-compose(.dev).yml files because it was obsolete:

WARN[0000] /home/antti/Documents/voting-advice-application/docker-compose.dev.yml: `version` is obsolete

Unnecessarry -- has been removed from yarn commands in Dockerfiles:

warning From Yarn 1.0 onwards, scripts don't require "--" for options to be forwarded. In a future version, any explicit "--" will be forwarded as-is to the scripts.

candidate field has been added to Strapi plugin config:

warn: Users-permissions registration has defaulted to accepting the following additional user fields during registration: candidate

Strapi data transfer feature has been disabled because it is not used:

Warning: Missing transfer.token.salt: Data transfer features have been disabled.
Please set transfer.token.salt in config/admin.js (ex: you can generate one using Node with `crypto.randomBytes(16).toString('base64')`)

Following warning can't be fixed by us. There is issue about it in the repo of the package but it hasn't been fixed.

[vite-plugin-svelte] WARNING: The following packages have a svelte field in their package.json but no exports condition for svelte.
[email protected]
Please see https://github.com/sveltejs/vite-plugin-svelte/blob/main/docs/faq.md#missing-exports-condition for details.

Check off each of the following tasks as they are completed

• I have reviewed the changes myself in this PR. Please check the self-review document
• I have added or edited unit tests.
• I have run the unit tests successfully.
• I have run the e2e tests successfully.
• I have tested this change on my own device.
• I have tested this change on other devices (Using Browserstack is recommended).
• I have tested my changes using the WAVE extension
• I have added documentation where necessary.
• Is there an existing issue linked to this PR?

Clean up your git commit history before submitting the pull request!

[kaljarv]

Could you also check if you can fix the maildev health check issue, which fails the e2e tests? On a quick look, this seems like a promising discussion: maildev/maildev#484

[kaljarv]

Strangely enough, now the Strapi container becomes unhealthy. @anolpe, could you investigate this contagion?

[kaljarv]

LGTM