ci: authenticate tflint init

[ferrarimarco]

Proposed changes

TFLint init might hit an API rate limit, especially when requests to the TFLint backend come from shared tenants, such as GitHub Actions.

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.

Super-linter maintainer tasks

• Label as breaking if this change breaks compatibility with the previous released version.
• Label as either: automation, bug, documentation, enhancement, infrastructure.
• Add the pull request to a milestone, eventually creating one, that matches with the version that release-please proposes.