Install numpy first

.github/workflows/build.yaml

@@ -24,9 +24,9 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
+        pip install coveralls 'numpy<1.20'
         pip install -r requirements.pip
         pip install -r test_requirements.pip
-        pip install coveralls
     - name: Run tests
       run: nosetests --with-coverage
     - name: Coveralls report