fix(deps): update dependency @netlify/serverless-functions-api to v1.18.3 (#504)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
|
[@netlify/serverless-functions-api](https://togithub.com/netlify/serverless-functions-api)
| [`1.18.2` ->
`1.18.3`](https://renovatebot.com/diffs/npm/@netlify%2fserverless-functions-api/1.18.2/1.18.3)
|
[![age](https://developer.mend.io/api/mc/badges/age/npm/@netlify%2fserverless-functions-api/1.18.3?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![adoption](https://developer.mend.io/api/mc/badges/adoption/npm/@netlify%2fserverless-functions-api/1.18.3?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![passing](https://developer.mend.io/api/mc/badges/compatibility/npm/@netlify%2fserverless-functions-api/1.18.2/1.18.3?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/npm/@netlify%2fserverless-functions-api/1.18.2/1.18.3?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

---

### Release Notes

<details>
<summary>netlify/serverless-functions-api
(@&#8203;netlify/serverless-functions-api)</summary>

###
[`v1.18.3`](https://togithub.com/netlify/serverless-functions-api/compare/e0bfbd4395ee4cf67abe5dfbd0f10dcd15e012aa...c6e6f3ca80e4087965e25d38cba063db310d340f)

[Compare
Source](https://togithub.com/netlify/serverless-functions-api/compare/e0bfbd4395ee4cf67abe5dfbd0f10dcd15e012aa...c6e6f3ca80e4087965e25d38cba063db310d340f)

</details>

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