Bump which from 5.0.0 to 6.0.0 in /proxy (#24)

Bumps [which](https://github.com/npm/node-which) from 5.0.0 to 6.0.0.
- [Release notes](https://github.com/npm/node-which/releases)
- [Changelog](https://github.com/npm/node-which/blob/main/CHANGELOG.md)
- [Commits](npm/node-which@v5.0.0...v6.0.0)

---
updated-dependencies:
- dependency-name: which
  dependency-version: 6.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

proxy/package-lock.json

@@ -33,7 +33,7 @@
   },
   "homepage": "https://github.com/elisp-lsp/ellsp#readme",
   "dependencies": {
-    "which": "^5.0.0"
+    "which": "^6.0.0"
   },
   "devDependencies": {
     "@yao-pkg/pkg": "^6.0.0"