Reset and exercise poetry caches

.github/actions/install-env/action.yml

@@ -26,7 +26,7 @@ runs:
       uses: actions/cache@v4
       with:
         path: ~/.local # the path depends on the OS
-        key: poetry-2 # increment to reset cache
+        key: poetry-3 # increment to reset cache
 
     - name: Install poetry
       uses: snok/install-poetry@v1