separate req's for testing suite

.github/workflows/tests.yaml

@@ -20,7 +20,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install flake8 pytest
-          if [ -f requirements.txt ]; then cat requirements.txt | xargs -L1 pip install --no-cache-dir; fi
+          if [ -f _requirements.txt ]; then pip install -r _requirements.txt; fi
       - name: Lint with flake8
         run: |
           # stop the build if there are Python syntax errors or undefined names

_requirements.txt

@@ -0,0 +1,3 @@
+pandas==1.5.3
+numba==0.56.4
+scipy==1.11.4