Update actions/checkout action to v7

Author: renovate[bot]

.github/workflows/build.yml

@@ -13,7 +13,7 @@ jobs:
       matrix:
         python-version: ['3.7', '3.8', '3.9', '3.10']
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v7
 
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v4