fix: upgrade @vercel/nft (sveltejs#15400)

closes sveltejs#13764
closes sveltejs#15349

We landed a fix in vercel/nft#568 that should
prevent system files from being copied into the function bundle.

---

### Please don't delete this checklist! Before submitting the PR, please
make sure you do the following:
- [x] It's really useful if your PR references an issue where it is
discussed ahead of time. In many cases, features are absent for a
reason. For large changes, please create an RFC:
https://github.com/sveltejs/rfcs
- [x] This message body should clearly illustrate what problems it
solves.
- [ ] Ideally, include a test that fails without this PR but passes with
it.
No test unless we want a test app that attempts to exceed the function
bundle size

### Tests
- [ ] Run the tests with `pnpm test` and lint the project with `pnpm
lint` and `pnpm check`

### Changesets
- [x] If your PR makes a change that should be noted in one or more
packages' changelogs, generate a changeset by running `pnpm changeset`
and following the prompts. Changesets that add features should be
`minor` and those that fix bugs should be `patch`. Please prefix
changeset messages with `feat:`, `fix:`, or `chore:`.

### Edits

- [x] Please ensure that 'Allow edits from maintainers' is checked. PRs
without this option may be closed.

Author: teemingc

.changeset/sad-plants-bow.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-vercel': patch
+---
+
+fix: ensure build does not copy Vercel build environment system files

packages/adapter-vercel/package.json

@@ -40,7 +40,7 @@
 		"test": "vitest run"
 	},
 	"dependencies": {
-		"@vercel/nft": "^1.0.0",
+		"@vercel/nft": "^1.3.2",
 		"esbuild": "^0.25.4"
 	},
 	"devDependencies": {