try to fix the warnings:

1. Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/checkout@v2, actions/setup-python@v2. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.

2. The following actions uses node12 which is deprecated and will be forced to run on node16: actions/checkout@v2, actions/setup-python@v2. For more info: https://github.blog/changelog/2023-06-13-github-actions-all-actions-will-run-on-node16-instead-of-node12-by-default/

.github/workflows/ci.yml

@@ -12,10 +12,10 @@ jobs:
 
     steps:
     - name: Checkout code
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
 
     - name: Set up Python
-      uses: actions/setup-python@v2
+      uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python-version }}
 
@@ -26,4 +26,4 @@ jobs:
 
     - name: Run tests
       run: |
-        pytest
+        pytest