build(deps): bump actions/setup-node from 4 to 6

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

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/ci.yaml

@@ -27,7 +27,7 @@ jobs:
       - run: git fetch --prune --unshallow
       - run: git config --global user.name 'Actions'
       - run: git config --global user.email '[email protected]'
-      - uses: actions/setup-node@v4
+      - uses: actions/setup-node@v6
         with:
           node-version: ${{ matrix.node }}
       - run: node --version

.github/workflows/release-please.yml

@@ -19,7 +19,7 @@ jobs:
         # these if statements ensure that a publication only occurs when
         # a new release is created:
         if: ${{ steps.release.outputs.release_created }}
-      - uses: actions/setup-node@v4
+      - uses: actions/setup-node@v6
         with:
           node-version: 20
           registry-url: 'https://registry.npmjs.org'