Add conftest back for adjoint tape clearing

test_adjoint/conftest.py

@@ -0,0 +1,8 @@
+
+
+def pytest_runtest_teardown(item, nextitem):
+    """Clear Thetis caches after running a test"""
+    from pyadjoint import get_working_tape
+
+    # clear the adjoint tape, so subsequent tests don't interfere
+    get_working_tape().clear_tape()