change req and workflow for numpy, install numpy explicitly in workflow

.github/workflows/pythonapp.yml

@@ -16,6 +16,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
+        pip install numpy cython
         pip3 install -r requirements.txt
     - name: Lint with flake8
       run: |

requirements.txt

@@ -1,6 +1,5 @@
 IPTCInfo3==2.1.4
 imageio==2.6.1
-numpy>=1.17
 rawpy==0.13.1
 setuptools==40.8.0
 Click==7.0