add python matrix for back tests

.github/workflows/main.yml

@@ -6,6 +6,9 @@ on:
 jobs:
   backend-tests:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: [3.8, 3.9, 3.10]
     services:
       postgres:
         image: postgres
@@ -17,11 +20,12 @@ jobs:
           - 5432:5432
         options: --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 5
     steps:
-    - uses: actions/checkout@v4
-    - name: Set up Python
+    - name: Checkout Repository
+      uses: actions/checkout@v4
+    - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v5
       with:
-        python-version: 3.9
+        python-version: ${{ matrix.python-version }}
 
     - name: Install dependencies
       run: |