Update GitHub Actions to checkout@v4 and setup-python@v5

PiperOrigin-RevId: 638207877

Author: mbrukman

.github/workflows/build.yml

@@ -23,9 +23,9 @@ jobs:
       uses: styfle/cancel-workflow-action@0.8.0
       with:
         access_token: ${{ github.token }}
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v1
+      uses: actions/setup-python@v5
       with:
         python-version: ${{ matrix.python-version }}
     - name: Install dependencies