fix: add code checkout and Python setup steps to lint workflow

Author: ShawnDen-coder

.github/workflows/lint.yaml

@@ -26,8 +26,13 @@ jobs:
     needs: setup
     runs-on: ubuntu-latest
     steps:
-      - name: Check Python version
-        run: python --version
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
 
       - name: Run lint checks
         id: lint
@@ -58,6 +63,14 @@ jobs:
     needs: setup
     runs-on: ubuntu-latest
     steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
       - name: Run tests on all Python versions
         id: test
         run: uvx nox -s test_all