Bump pnpm/action-setup from 4 to 6

Bumps [pnpm/action-setup](https://github.com/pnpm/action-setup) from 4 to 6.
- [Release notes](https://github.com/pnpm/action-setup/releases)
- [Commits](pnpm/action-setup@v4...v6)

---
updated-dependencies:
- dependency-name: pnpm/action-setup
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/main.yaml

@@ -36,7 +36,7 @@ jobs:
         with:
           node-version-file: ".nvmrc"
       # pnpm is needed for test fixtures that use packageManager: pnpm
-      - uses: pnpm/action-setup@v4
+      - uses: pnpm/action-setup@v6
         with:
           version: 10