Add #2855 changelog entry

Author: tyt2y3

changelog/2.0.0-rc.41.md

@@ -63,6 +63,14 @@ model is not needed. Unlike `update`, it runs `before_save` but skips
 
 ### Bug Fixes
 
+**`serde(rename_all)` no longer breaks `ActiveModel::from_json` defaulting** (#2855, #2854)
+
+Regression from #2842: a `#[serde(rename_all = "...")]` container attribute (or
+field-level `#[serde(rename = "...")]`) caused `ActiveModel::from_json` to error
+with "missing field" instead of defaulting missing fields to `ActiveValue::NotSet`.
+The default-merge is now keyed off each column's `json_key()`, which respects both
+`rename_all` and field-level renames.
+
 **Schema-sync indexes for non-default PostgreSQL schemas** (#3085, #3084)
 
 Indexes generated from `#[sea_orm(indexed)]` and `#[sea_orm(unique_key = "...")]`