Worflows CI testing

.github/workflows/ubuntu.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.6, 3.7, 3.8]
+        python-version: [3.7, 3.8]
     steps:
     - uses: actions/checkout@v2
     - name: Set up Python ${{ matrix.python-version }}
@@ -21,10 +21,10 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
+        # Until the next xdis release
+        pip install git+git://github.com/rocky/python-xdis.git#egg=xdis
         pip install -e .
-    - name: Install prerequisits
-      run: |
-        pip install -e .
-    - name: Test Mathics Scanner
+        pip install -r requirements-dev.txt
+    - name: Test uncompyle6
       run: |
         make check