build: automatically set scalafmt version

[ferrarimarco]

Automatically append the 'version' configuration parameter to the scalafmt configuration file when building the image instead of using a GitHub Actions workflow to keep the scalafmt configuration file up to date. This makes the building process more reproducible and self-contained in the Dockerfile, and it also avoid stalling Dependabot PRs that update scalafmt because when there are automatically added commits to a PR, they block triggering workflows for that PR.

Readiness checklist

In order to have this pull request merged, complete the following tasks.

Pull request author tasks

• I checked that all workflows return a success.
• I included all the needed documentation for this change.
• I provided the necessary tests.
• I squashed all the commits into a single commit.
• I followed the Conventional Commit v1.0.0 spec.
• I wrote the necessary upgrade instructions in the upgrade guide.
• If this pull request is about and existing issue,
  I added the Fix #ISSUE_NUMBER or Close #ISSUE_NUMBER text to the description of the pull request.

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• Label as breaking if this change breaks compatibility with the previous released version.
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