Get tests working on Linux

.github/workflows/pytest.yaml

@@ -39,6 +39,9 @@ jobs:
           ~\AppData\Local\pip\Cache  # Windows
         key: ${{ runner.os }}-python-${{ matrix.python-version }}-${{ hashFiles('requirements.txt') }}
         restore-keys: ${{ runner.os }}-python-${{ matrix.python-version }}-
+    - name: Install apt dependencies
+      run: sudo apt-get install unrar
+      if: ${{ runner.os == 'Linux' }}
     - name: Install conda
       uses: conda-incubator/setup-miniconda@v2
       with: