Update GitHub action

Author: edemaine

.github/workflows/tests.yml

@@ -7,13 +7,13 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Install Node
-        uses: actions/setup-node@v1
+        uses: actions/setup-node@v4
         with:
-          node-version: '14'
+          node-version: '20'
       - name: Cache dependencies
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: |
             node_modules