Add standalone sane-fmt checker to GitHub workflow

Author: KSXGitHub

.github/workflows/nodejs.yml

@@ -41,6 +41,9 @@ jobs:
           - id: 5
             node: 14.x
             pnpm: --frozen-lockfile
+          - id: 6
+            node: 14.x
+            cmd: pnpm run sane-fmt -- --log-format=github-actions --details=diff
     steps:
       - uses: actions/checkout@v1
       - name: Use Node.js ${{ matrix.vars.node }}