Issue #619: Update tests after data.table update

[nikosbosse]

Description

This PR fixes #619.

As mentioned by @seabbs in #616, the recent update of data.table requires an update to our test snaps. This PR fixes this.

Checklist

• My PR is based on a package issue and I have explicitly linked it.
• I have included the target issue or issues in the PR title as follows: issue-number: PR title
• I have tested my changes locally.
• I have added or updated unit tests where necessary.
• I have updated the documentation if required.
• I have built the package locally and run rebuilt docs using roxygen2.
• My code follows the established coding standards and I have run lintr::lint_package() to check for style issues introduced by my changes.
• I have added a news item linked to this PR.
• I have reviewed CI checks for this PR and addressed them as far as I am able.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (14a77e8) 85.77% compared to head (a84f0e1) 85.77%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #618   +/-   ##
=======================================
  Coverage   85.77%   85.77%           
=======================================
  Files          21       21           
  Lines        1758     1758           
=======================================
  Hits         1508     1508           
  Misses        250      250           

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