update flopy in CI

Author: wpbonelli

.github/workflows/ci.yml

@@ -156,6 +156,10 @@ jobs:
           pip install -r requirements.pip.txt
           pip install -r requirements.usgs.txt
 
+      - name: Update flopy
+        working-directory: modflow6/autotest
+        run: python update_flopy.py
+
       - name: Build modflow6 example models
         if: steps.cache-examples.outputs.cache-hit != 'true'
         working-directory: modflow6-examples/etc