Removing poetry cache so it stops it from cleaning up

.github/workflows/unit_tests.yaml

@@ -45,7 +45,6 @@ jobs:
       - uses: actions/[email protected]
         with:
           python-version: '3.9'
-          cache: 'poetry'
       - name: Install python dependencies and check code
         run: |
           poetry env use '3.9'