Update CHANGELOG for Swift-based schema download

Author: calvincestari

CHANGELOG.md

@@ -1,5 +1,8 @@
 # Change log
 
+## v0.49.0
+- **Breaking - Schema download is now Swift-based:** The dependency on the Apollo CLI (Typescript-based) for schema downloading has been removed. Schema downloads are now Swift-based and maintainable/extensible within apollo-ios. This is a breaking change because Some of the API signatures have changed. [#1935](https://github.com/apollographql/apollo-ios/pull/1935)
+
 ## v0.48.0
 - **Customizable subscription message identifiers:** The `WebSocketTransport` initializer can be configured with a subclass of `OperationMessageIdCreator` to provide a unique identifier per request. The default implementation is `ApolloSequencedOperationMessageIdCreator` and retains the current behavior of sequential message numbering. [#1919](https://github.com/apollographql/apollo-ios/pull/1919) - _Thank you to [Clark McNally](https://github.com/cmcnally-beachbody) for the contribution!_
 - **AWS AppSync Compatibility:** Apollo-ios will now correctly handle the `start_ack` message that AWS AppSync servers respond with when a subscription is requested. [#1919](https://github.com/apollographql/apollo-ios/pull/1919) - _Thank you to [Clark McNally](https://github.com/cmcnally-beachbody) for the contribution!_