fix: check for regex in external

[JuanoD]

Description

This fixes #556. Tests every shared item using every regex.

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What is the purpose of this pull request?

• [X] Bug fix
• [ ] New Feature
• [ ] Documentation update
• [ ] Other

Before submitting the PR, please make sure you do the following

• [X] Read the Code of Conduct and follow the Commit Convention guidelines.
• [X] Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• [X] Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• [ ] Ideally, include relevant tests that fail without this PR but pass with it.