chore(deps): bump pnpm (#9800)

Bumps the test-versions group with 1 update in the /packages/dd-trace/test/plugins/versions directory: [pnpm](https://github.com/pnpm/pnpm/tree/HEAD/pnpm11/pnpm).


Updates `pnpm` from 11.20.0 to 11.21.0
- [Release notes](https://github.com/pnpm/pnpm/releases)
- [Commits](https://github.com/pnpm/pnpm/commits/v11.21.0/pnpm11/pnpm)

---
updated-dependencies:
- dependency-name: pnpm
  dependency-version: 11.21.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: test-versions
...

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Author: dependabot[bot]

packages/dd-trace/test/plugins/versions/package.json

@@ -206,7 +206,7 @@
     "pino-pretty": "13.1.3",
     "playwright": "1.62.1",
     "playwright-core": "1.62.1",
-    "pnpm": "11.20.0",
+    "pnpm": "11.21.0",
     "prisma": "7.9.1",
     "promise": "8.3.0",
     "promise-js": "0.0.7",