Add astropy to CI test deps (waveform package imports it for detector geometry)

Author: nnarenraju

.github/workflows/ci.yml

@@ -69,7 +69,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install torch --index-url https://download.pytorch.org/whl/cpu
-          pip install numpy scipy tqdm h5py matplotlib scikit-learn pytest pytest-cov ribs
+          pip install numpy scipy tqdm h5py matplotlib scikit-learn pytest pytest-cov ribs astropy
           pip install -e . --no-deps
 
       - name: Run tests with coverage