Bump GitHub Actions versions to use Node.JS 20

Node.JS 16 actions are deprecated, leading to CI warnings.

.github/workflows/ci.yaml

@@ -26,10 +26,10 @@ jobs:
     name: Typecheck, lint, and check code style
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Set up Python
-        uses: actions/setup-python@v4
+        uses: actions/setup-python@v5
         with:
           python-version: "3.10"
 
@@ -87,10 +87,10 @@ jobs:
           - pytest74-xdist
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Set up Python
-        uses: actions/setup-python@v4
+        uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python }}
 
@@ -120,10 +120,10 @@ jobs:
       - pytest_integration_tests
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Set up Python
-        uses: actions/setup-python@v4
+        uses: actions/setup-python@v5
         with:
           python-version: "3.10"