Bump actions/checkout to v4 (to suppress old Node version warning)

Author: JamesParrott

.github/workflows/build.yml

@@ -33,7 +33,7 @@ jobs:
       image: python:${{ matrix.python-version }}-slim
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip

.github/workflows/deploy.yml

@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Set up Python
       uses: actions/setup-python@v2
       with: