Fix CI cache

Author: Sébastien Eustace

.github/workflows/tests.yml

@@ -85,7 +85,7 @@ jobs:
       uses: actions/cache@v1
       with:
         path: .venv
-        key: venv-${{ runner.os }}-${{ steps.full-python-version.outputs.version }}-${{ hashFiles('**/poetry.lock') }}
+        key: venv-${{ runner.os }}-${{ steps.full-python-version.outputs.version }}-fix-${{ hashFiles('**/poetry.lock') }}
     - name: Install dependencies
       run: |
         source $HOME/.poetry/env