chore(deps): bump pnpm/action-setup from 2 to 3 (MisskeyIO#422)

Bumps [pnpm/action-setup](https://github.com/pnpm/action-setup) from 2 to 3.
- [Release notes](https://github.com/pnpm/action-setup/releases)
- [Commits](https://github.com/pnpm/action-setup/compare/v2...v3)

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

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

.github/workflows/test-frontend.yml

@@ -32,7 +32,7 @@ jobs:
       with:
         submodules: true
     - name: Install pnpm
-      uses: pnpm/action-setup@v2
+      uses: pnpm/action-setup@v3
       with:
         version: 8
         run_install: false
@@ -90,7 +90,7 @@ jobs:
     #- uses: browser-actions/setup-firefox@latest
     #  if: ${{ matrix.browser == 'firefox' }}
     - name: Install pnpm
-      uses: pnpm/action-setup@v2
+      uses: pnpm/action-setup@v3
       with:
         version: 8
         run_install: false