Bump actions/setup-node from 2.3.0 to 2.3.1

Bumps [actions/setup-node](https://github.com/actions/setup-node) from 2.3.0 to 2.3.1.
- [Release notes](https://github.com/actions/setup-node/releases)
- [Commits](https://github.com/actions/setup-node/compare/v2.3.0...v2.3.1)

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

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

.github/workflows/autoprefixer.yml

@@ -11,7 +11,7 @@ jobs:
         uses: actions/checkout@v2.3.4
 
       - name: Setup Node
-        uses: actions/setup-node@v2.3.0
+        uses: actions/setup-node@v2.3.1
         with:
           node-version: "15.x"