client-api: allow constructing ErrorBody::NotJson

crates/ruma-client-api/CHANGELOG.md

@@ -37,6 +37,7 @@ Improvements:
 - Add the `get_login_token` field to `Capabilities`, according to a
   clarification in the spec.
 - Add support for account locking, according to MSC3939.
+- Allow constructing `error::ErrorBody::NotJson` outside of this crate.
 
 Bug fixes:
 

crates/ruma-client-api/src/error.rs

@@ -316,7 +316,6 @@ pub enum ErrorBody {
     Json(JsonValue),
 
     /// A response body that is not valid JSON.
-    #[non_exhaustive]
     NotJson {
         /// The raw bytes of the response body.
         bytes: Bytes,