build(deps): 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](https://github.com/pnpm/action-setup/compare/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>

.github/workflows/ci-web.yml

@@ -35,7 +35,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Set pnpm
-        uses: pnpm/action-setup@v4
+        uses: pnpm/action-setup@v6
         with:
           package_json_file: dc3-web/package.json
 
@@ -75,7 +75,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Set pnpm
-        uses: pnpm/action-setup@v4
+        uses: pnpm/action-setup@v6
         with:
           package_json_file: dc3-web/package.json
 

.github/workflows/docs.yml

@@ -35,7 +35,7 @@ jobs:
           fetch-depth: 0
 
       - name: Setup pnpm
-        uses: pnpm/action-setup@v4
+        uses: pnpm/action-setup@v6
         with:
           package_json_file: docs/package.json
           run_install: false