Fix unittest action

.github/workflows/run-unittests.yaml

@@ -19,7 +19,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install pytest pytest-cov statsmodels python-datamatrix matplotlib
+          pip install pytest pytest-cov statsmodels datamatrix matplotlib
       - name: Test with pytest
         run: |
           pytest --cov=time_series_test unittests/