Splitting GI to system dependency

.github/workflows/python-tests.yml

@@ -17,10 +17,12 @@ jobs:
       uses: actions/setup-python@v2
       with:
         python-version: ${{ matrix.python-version }}
-    - name: Install dependencies
+    - name: Install system dependencies
+      run: apt-get install python3-gi
+    - name: Install python dependencies
       run: |
         python3 -m pip install --upgrade pip
-        python3 -m pip install tox tox-gh-actions python3-gi
+        python3 -m pip install tox tox-gh-actions
         python3 -m pip install -e .
     - name: Test with tox
       run: tox