Fix CLI test & GitHub action

.github/workflows/tests.yml

@@ -8,18 +8,18 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-    - name: Install ghostscript libmagickwand-dev
-      run: sudo apt-get install libxml2-utils
+    - name: Prepare for installations
+      run: sudo apt update -y
+    - name: Install Python
+      run: sudo apt install -y python3-pip python3-dev python3-venv
+    - name: Install ghostscript & imagemagick
+      run: sudo apt install -y ghostscript libmagickwand-dev
     - name: Remove policy.xml
       run: sudo rm /etc/ImageMagick-6/policy.xml
     - name: Check out repo
       uses: actions/checkout@v2
-    - name: Set up Python
-      uses: actions/setup-python@v1
-      with:
-        python-version: 3.8
-    - uses: actions/cache@v2
-      name: Configure pip caching
+    - name: Configure pip caching
+      uses: actions/cache@v2
       with:
         path: ~/.cache/pip
         key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt')}}-${{ hashFiles('**/requirements-dev.txt') }}
@@ -31,5 +31,5 @@ jobs:
       run: make check-flake
     - name: Run tests
       run: make tests
-    - name: Examine code coverage
+    - name: Upload code coverage
       uses: codecov/codecov-action@v1.0.12