Closes #246 Remove {metatools} dependency

[arjoon-r]

Thank you for your Pull Request! We have developed this task checklist from the Development Process Guide to help with the final steps of the process. Completing the below tasks helps to ensure our reviewers can maximize their time on your code as well as making sure the admiral codebase remains robust and consistent.

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• Updated relevant unit tests or have written new unit tests - See Unit Test Guide
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• Run devtools::document() so all .Rd files in the man folder and the NAMESPACE file in the project root are updated appropriately
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• Update NEWS.md if the changes pertain to a user-facing function (i.e. it has an @export tag) or documentation aimed at users (rather than developers)
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• Link the issue so that it closes after successful merging.
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[github-actions]

Package	Line Rate	Health
admiralvaccine	99%	✔
Summary	99% (369 / 372)	✔