ci: use Python 3.6 and above for mypy analysis

Signed-off-by: César Román <thecesrom@gmail.com>

.github/workflows/ci.yml

@@ -6,13 +6,15 @@ jobs:
   build:
 
     runs-on: ubuntu-latest
-
+    strategy:
+      matrix:
+        python-version: ["3.6", "3.7", "3.8", "3.9", "3.10", "3.11"]
     steps:
     - uses: actions/checkout@v3
-    - name: Set up Python 3
+    - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v4
       with:
-        python-version: '3.10'
+        python-version: ${{ matrix.python-version }}
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip