Update changelog file (#6825)

Author: rlazo

firebase-dataconnect/CHANGELOG.md

@@ -1,7 +1,4 @@
 # Unreleased
-* [changed] Removed the "beta" suffix from the version of the Firebase Data
-  Connect Android SDK, thus graduating it from "beta" to "generally available".
-  ([#6792](https://github.com/firebase/firebase-android-sdk/pull/6792))
 * [changed] DataConnectOperationException added, enabling support for partial
   errors; that is, any data that was received and/or was able to be decoded is
   now available via the "response" property of the exception thrown when a