fix(deps): update dependency astro to v4.16.15 (#423)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [astro](https://astro.build)
([source](https://redirect.github.com/withastro/astro/tree/HEAD/packages/astro))
| [`4.16.14` ->
`4.16.15`](https://renovatebot.com/diffs/npm/astro/4.16.14/4.16.15) |
[![age](https://developer.mend.io/api/mc/badges/age/npm/astro/4.16.15?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![adoption](https://developer.mend.io/api/mc/badges/adoption/npm/astro/4.16.15?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![passing](https://developer.mend.io/api/mc/badges/compatibility/npm/astro/4.16.14/4.16.15?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/npm/astro/4.16.14/4.16.15?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

---

### Release Notes

<details>
<summary>withastro/astro (astro)</summary>

###
[`v4.16.15`](https://redirect.github.com/withastro/astro/blob/HEAD/packages/astro/CHANGELOG.md#41615)

[Compare
Source](https://redirect.github.com/withastro/astro/compare/[email protected]@4.16.15)

##### Patch Changes

-
[#&#8203;12498](https://redirect.github.com/withastro/astro/pull/12498)
[`b140a3f`](https://redirect.github.com/withastro/astro/commit/b140a3f6d821127f927b7cb938294549e41c5168)
Thanks [@&#8203;ematipico](https://redirect.github.com/ematipico)! -
Fixes a regression where Astro was trying to access `Request.headers`

</details>

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