chore(deps-dev): bump undici in /packages/socket-mode

Bumps [undici](https://github.com/nodejs/undici) from 7.28.0 to 8.7.0.
- [Release notes](https://github.com/nodejs/undici/releases)
- [Commits](nodejs/undici@v7.28.0...v8.7.0)

---
updated-dependencies:
- dependency-name: undici
  dependency-version: 8.7.0
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

packages/socket-mode/package.json

@@ -66,7 +66,7 @@
     "proxyquire": "^2.1.3",
     "sinon": "^22",
     "tsd": "^0.33.0",
-    "undici": "^7.25.0",
+    "undici": "^8.7.0",
     "ws": "^8"
   },
   "tsd": {