Bump node environment to 16.x

- Bump setup-node action to v2.
- Use composite actions to reuse same setting. This is preferred over
  reusable templates because reusable templates are on job-level but
  setting up node should be a step.

.github/workflows/release.desktop.yaml

@@ -20,9 +20,7 @@ jobs:
       - name: Checkout to bump commit
         run: git checkout "$(git rev-list "${{ github.event.release.tag_name }}"..master | tail -1)"
       - name: Setup node
-        uses: actions/setup-node@v1
-        with:
-          node-version: 15.x
+        uses: ./.github/actions/setup-node
       - name: Install dependencies
         run: npm ci
       - name: Run unit tests
@@ -31,4 +29,4 @@ jobs:
         run: npm run electron:build -- -p always # https://nklayman.github.io/vue-cli-plugin-electron-builder/guide/recipes.html#upload-release-to-github
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-          EP_GH_IGNORE_TIME: true # Otherwise publishing fails if GitHub release is more than 2 hours old https://github.com/electron-userland/electron-builder/issues/2074
+          EP_GH_IGNORE_TIME: true # Otherwise publishing fails if GitHub release is more than 2 hours old https://github.com/electron-userland/electron-builder/issues/2074