chore(deps): bump pulumi/actions from 3 to 6

Bumps [pulumi/actions](https://github.com/pulumi/actions) from 3 to 6.
- [Release notes](https://github.com/pulumi/actions/releases)
- [Changelog](https://github.com/pulumi/actions/blob/main/CHANGELOG.md)
- [Commits](pulumi/actions@v3...v6)

---
updated-dependencies:
- dependency-name: pulumi/actions
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/cd.yaml

@@ -38,15 +38,15 @@ jobs:
 
       - name: PR previews
         if: ${{ github.event_name == 'pull_request' }}
-        uses: pulumi/actions@v3
+        uses: pulumi/actions@v6
         with:
           command: preview
           stack-name: ${{ env.PULUMI_STACK_NAME }}
           work-dir: ${{ env.PULUMI_WORKING_DIRECTORY }}
 
       - name: Apply infrastructure update
         if: ${{ github.event_name == 'push' }}
-        uses: pulumi/actions@v3
+        uses: pulumi/actions@v6
         with:
           command: up
           stack-name: ${{ env.PULUMI_STACK_NAME }}