Fix CI

.github/workflows/ci.yml

@@ -6,19 +6,14 @@ on:
 jobs:
   python-test-backend:
     name: 🧪 Test backend Python code
-    strategy:
-      matrix:
-        python-version:
-        - '3.6'
-        - '3.8'
     runs-on: ubuntu-latest
     steps:
     - name: 📥 Check-out
       uses: actions/checkout@v4
     - name: 🧰 Install Python
       uses: actions/setup-python@v5
       with:
-        python-version: ${{ matrix.python-version }}
+        python-version: '3.8'
         cache: pip
         cache-dependency-path: src/Backend/Pipfile.lock
     - name: 🧰 Install Pipenv