CI: install pooch for ndimage

Author: ev-br

.github/workflows/pip.yml

@@ -70,5 +70,6 @@ jobs:
 
     - name: Run testmod a scipy submodule -- Public API onlly
       run: |
+        python -mpip install pooch
         python -c'from scipy import ndimage; from scpdt import testmod; testmod(ndimage, verbose=True, strategy="api")'