Enable caching

Author: nwoodruff-co

changelog_entry.yaml

@@ -0,0 +1,4 @@
+- bump: patch
+  changes:
+    fixed:
+    - Caching didn't save time!

src/policyengine/core/simulation.py

@@ -31,6 +31,7 @@ def ensure(self):
         cached_result = _cache.get(self.id)
         if cached_result:
             self.output_dataset = cached_result.output_dataset
+            return
         try:
             self.tax_benefit_model_version.load(self)
         except Exception: