Update dependency undici to v6.15.0 (#952)

[![Mend Renovate](https://app.renovatebot.com/images/banner.svg)](https://renovatebot.com)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [undici](https://undici.nodejs.org) ([source](https://togithub.com/nodejs/undici)) | [`6.14.1` -> `6.15.0`](https://renovatebot.com/diffs/npm/undici/6.14.1/6.15.0) | [![age](https://developer.mend.io/api/mc/badges/age/npm/undici/6.15.0?slim=true)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://developer.mend.io/api/mc/badges/adoption/npm/undici/6.15.0?slim=true)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://developer.mend.io/api/mc/badges/compatibility/npm/undici/6.14.1/6.15.0?slim=true)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://developer.mend.io/api/mc/badges/confidence/npm/undici/6.14.1/6.15.0?slim=true)](https://docs.renovatebot.com/merge-confidence/) |

---

> [!WARNING]
> Some dependencies could not be looked up. Check the Dependency Dashboard for more information.

---

### Release Notes

<details>
<summary>nodejs/undici (undici)</summary>

### [`v6.15.0`](https://togithub.com/nodejs/undici/releases/tag/v6.15.0)

[Compare Source](https://togithub.com/nodejs/undici/compare/v6.14.1...v6.15.0)

#### What's Changed

-   Expose EnvHttpProxyAgent to Node.js core bundle, so it can be turned … by [@&#8203;mcollina](https://togithub.com/mcollina) in [nodejs/undici#3148
-   test: add headerslist copy check by [@&#8203;tsctx](https://togithub.com/tsctx) in [nodejs/undici#3156
-   chore: ensure automated v6 release compared to v6 by [@&#8203;mweberxyz](https://togithub.com/mweberxyz) in [nodejs/undici#3149
-   fetch: do not leak signal listeners by [@&#8203;mcollina](https://togithub.com/mcollina) in [nodejs/undici#3158
-   fix: request cache mode is not the same as request mode by [@&#8203;tsibley](https://togithub.com/tsibley) in [nodejs/undici#3151
-   fetch: don't re-lowercase HeadersList by [@&#8203;tsctx](https://togithub.com/tsctx) in [nodejs/undici#3159
-   fix casing issue when cloning Headers object by [@&#8203;KhafraDev](https://togithub.com/KhafraDev) in [nodejs/undici#3160
-   build(deps): bump node from `6d0f18a` to `db8772d` in /build by [@&#8203;dependabot](https://togithub.com/dependabot) in [nodejs/undici#3163
-   fix header cloning bug by [@&#8203;tsctx](https://togithub.com/tsctx) in [nodejs/undici#3162
-   chore: change bench naming for h2 by [@&#8203;metcoder95](https://togithub.com/metcoder95) in [nodejs/undici#3165
-   expose WebSocket related events in node bundle by [@&#8203;KhafraDev](https://togithub.com/KhafraDev) in [nodejs/undici#3167
-   feat: add support for if-match on retry handler by [@&#8203;metcoder95](https://togithub.com/metcoder95) in [nodejs/undici#3144
-   fix: correct firing order of abort events by [@&#8203;tsctx](https://togithub.com/tsctx) in [nodejs/undici#3169
-   create fast MessageEvent by [@&#8203;KhafraDev](https://togithub.com/KhafraDev) in [nodejs/undici#3170
-   chore: add explicitly [@&#8203;fastify/busboy](https://togithub.com/fastify/busboy) by [@&#8203;Uzlopak](https://togithub.com/Uzlopak) in [nodejs/undici#3172
-   chore: remove sinon as dev dependency by [@&#8203;Uzlopak](https://togithub.com/Uzlopak) in [nodejs/undici#3171
-   webidl changes by [@&#8203;KhafraDev](https://togithub.com/KhafraDev) in [nodejs/undici#3175
-   preserve dictionary key name in webidl errors by [@&#8203;KhafraDev](https://togithub.com/KhafraDev) in [nodejs/undici#3176

#### New Contributors

-   [@&#8203;tsibley](https://togithub.com/tsibley) made their first contribution in [nodejs/undici#3151

**Full Changelog**: nodejs/undici@v6.14.1...v6.15.0

</details>

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update again.

---

 - [ ] If you want to rebase/retry this PR, check this box

---

This PR has been generated by [Mend Renovate](https://www.mend.io/free-developer-tools/renovate/). View repository job log [here](https://developer.mend.io/github/X-oss-byte/Canary-nextjs).

packages/next/package.json

@@ -279,7 +279,7 @@
     "timers-browserify": "2.0.12",
     "tty-browserify": "0.0.1",
     "ua-parser-js": "1.0.37",
-    "undici": "6.14.1",
+    "undici": "6.15.0",
     "unistore": "3.5.2",
     "util": "0.12.5",
     "uuid": "9.0.1",