Update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/test.yml

@@ -14,7 +14,7 @@ jobs:
         node: [ 10, 12 ]
     name: Node ${{ matrix.node }}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: actions/setup-node@v2
         with:
           node-version: ${{ matrix.node }}