fix: typo

.github/workflows/ci.yml

@@ -34,7 +34,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install pytest-xdist nbval
-          pip install -r requirements.txt
+          pip install -U -r requirements.txt
           pip install git+https://github.com/zfit/zfit
       - name: Run notebooks
         run: |