cache pip instead of poetry

.github/workflows/predict.yml

@@ -47,7 +47,7 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: '3.10'
-          cache: 'poetry'
+          cache: 'pip'
       - run: make install-prod
 
       # we need this step as ersilia will use the default conda environment to run the example model during `ersilia serve`