Update main.yml

Author: SkafteNicki

.github/workflows/main.yml

@@ -23,6 +23,7 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         pip install -r requirements.txt
+        pip install -r requirements_tests.txt
     - name: Install package
       run: |
         python setup.py install sdist bdist_wheel