clean virtual env

Author: nicolebalmer1-nhs

.github/workflows/continous-integration-workflow.yaml

@@ -24,7 +24,9 @@ jobs:
         run: pip install poetry
 
       - name: Install dependencies
-        run: poetry install
+        run: |
+          poetry env remove --all || true
+          poetry install
 
       - name: Set SPEC_VERSION env var
         run: echo ::set-env name=SPEC_VERSION::$(poetry run python scripts/calculate_version.py)