changelog: update changelog for 9.3.0
## 9.3.0 [version may change, pending release]
- Enter multisig account name on the device if the name in BTCRegisterScriptConfigRequest is empty.
+- Allow new keypaths: m/48'/coin'/account' for multisig, to enable compatibility with the Nunchuk wallet.
+- Multisig script type and derivation keypath are now also verified during account regisration.
