Reduced VAT share is 2.5% (#1340)

Author: janton10

changelog_entry.yaml

@@ -0,0 +1,4 @@
+- bump: minor
+  changes:
+    fixed:
+      - Update reduced vat expenditure share from OBR

policyengine_uk/parameters/gov/hmrc/vat/reduced_rate_share.yaml

@@ -3,8 +3,8 @@ metadata:
   economy: false
   propagate_metadata_to_children: true
   reference:
-  - href: https://obr.uk/forecasts-in-depth/tax-by-tax-spend-by-spend/vat/
-    title: OBR
+    - href: https://obr.uk/forecasts-in-depth/tax-by-tax-spend-by-spend/vat/
+      title: OBR
   unit: /1
 values:
-  2000-01-01: 0.03
+  2000-01-01: 0.025