build(deps): bump pnpm/action-setup from 5 to 6

Bumps [pnpm/action-setup](https://github.com/pnpm/action-setup) from 5 to 6.
- [Release notes](https://github.com/pnpm/action-setup/releases)
- [Commits](pnpm/action-setup@v5...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/4.1-nightly.yml

@@ -65,7 +65,7 @@ jobs:
           package-manager-cache: false
           node-version: 24.x
 
-      - uses: pnpm/action-setup@v5
+      - uses: pnpm/action-setup@v6
         name: Install pnpm
         id: pnpm-install
         with:

.github/workflows/build.yml

@@ -63,7 +63,7 @@ jobs:
           node-version: 24
 
       - name: Setup pnpm
-        uses: pnpm/action-setup@v5
+        uses: pnpm/action-setup@v6
         with:
           version: 8.15.5
           run_install: false

.github/workflows/dev-nightly.yml

@@ -63,7 +63,7 @@ jobs:
           package-manager-cache: false
           node-version: 24.x
 
-      - uses: pnpm/action-setup@v5
+      - uses: pnpm/action-setup@v6
         name: Install pnpm
         id: pnpm-install
         with: