Fix GHA failing due to lack of DAGSTER_HOME

.github/workflows/ci.yml

@@ -69,6 +69,8 @@ jobs:
         run: >-
           python -m pytest -ra --cov --cov-report=xml --cov-report=term
           --durations=20
+        env:
+          DAGSTER_HOME: ${{ runner.temp }}/dagster_home
 
       - name: Upload coverage report
         uses: codecov/[email protected]