finish changelog for 4.2.1 release

ChangeLog

@@ -3,7 +3,12 @@ CHANGES
 4.2.1
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 * administered_to, associated_with moved back to related_to in top level yaml
-
+* make sure treats hierarchy (mixin or not) has its ancestry in "related_to" - Richard B.
+* add "url" property to the model to support MolePro, non-curie expandable cross references. - Larry C.
+* add two statistical properties p-value and adjusted p-value to association class for use in Monarch KG. - Kevin S.
+* bump jinja2 from 3.1.3 to 3.1.4 - dependabot
+* bump tqdm from 4.66.1 to 4.66.3 - dependabot
+* add RO:0004029 narrow mapping to has_phenotype predicate to support Mondo KG - Kevin S.
 
 4.2.0
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