fix: deprecation warning

[SkeLLLa]

closes #71

[codecov[bot]]

Codecov Report

Base: 100.00% // Head: 100.00% // No change to project coverage :thumbsup:

Coverage data is based on head (3716df0) compared to base (c3290bd). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #72 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 2 2 Lines 139 137 -2 Branches 53 51 -2 ========================================= - Hits 139 137 -2 ``` | [Impacted Files](https://codecov.io/gh/SkeLLLa/fastify-metrics/pull/72?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Alex) | Coverage Δ | | |---|---|---| | [src/fastify-metrics.ts](https://codecov.io/gh/SkeLLLa/fastify-metrics/pull/72/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Alex#diff-c3JjL2Zhc3RpZnktbWV0cmljcy50cw==) | `100.00% <100.00%> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Alex). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Alex)

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