Manually install scipy

Note that this approach is problematic. Ideally the python package should define the dependency on scipy on its own and the installation of scipy should happen automatically.

.github/workflows/build-and-test.yml

@@ -32,6 +32,9 @@ jobs:
     steps:
       - name: Checkout Repository
         uses: actions/checkout@v2      
+      - name: Install scipy (see https://github.com/precice/fenics-adapter/issues/189)
+        run:  |
+          apt install python3-scipy
       - name: Install fake precice
         run:  |
           mkdir -p precice