Add installation of aspell

The package "aspell" should be installed anyway because "aspell-fr" depends on
it.

Author: flashcode

.github/workflows/tests.yml

@@ -19,7 +19,7 @@ jobs:
         python-version: ${{ matrix.python-version }}
     - name: Install dependencies
       run: |
-        sudo apt-get install gettext aspell-fr
+        sudo apt-get install gettext aspell aspell-fr
         python -m pip install --upgrade pip
         pip install -r requirements.txt
         pip install pytest