Upgrade GitHub actions

This updates the GitHub actions to remove the following warning:
"Node.js 16 actions are deprecated"

See: https://github.com/kuu/hls-parser/actions/runs/8570668225

.github/workflows/tests.yml

@@ -7,9 +7,9 @@ jobs:
       matrix:
         node-version: [ 'current', 'lts/*', 'lts/-1' ]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Setup Node ${{ matrix.node-version }}
-        uses: actions/setup-node@v3
+        uses: actions/setup-node@v4
         with:
           node-version: ${{ matrix.node-version }}
       - run: npm ci