client-api: allow /register to support authentication from appservices

crates/ruma-client-api/CHANGELOG.md

@@ -31,6 +31,7 @@ Improvements:
   according to MSC4025.
 - Allow `discovery::get_supported_versions::v1` to optionally accept
   authentication, according to MSC4026.
+- Allow `account::register::v3` to accept authentication for appservices.
 
 # 0.17.4
 

crates/ruma-client-api/src/account/register.rs

@@ -22,7 +22,7 @@ pub mod v3 {
     const METADATA: Metadata = metadata! {
         method: POST,
         rate_limited: true,
-        authentication: None,
+        authentication: AppserviceToken,
         history: {
             1.0 => "/_matrix/client/r0/register",
             1.1 => "/_matrix/client/v3/register",