add "unstable" endpoint legacy Element Android/iOS seems to call

Signed-off-by: strawberry <strawberry@puppygock.gay>

src/api/client/thirdparty.rs

@@ -2,7 +2,7 @@ use std::collections::BTreeMap;
 
 use ruma::api::client::thirdparty::get_protocols;
 
-use crate::{Result, Ruma};
+use crate::{Result, Ruma, RumaResponse};
 
 /// # `GET /_matrix/client/r0/thirdparty/protocols`
 ///
@@ -15,3 +15,13 @@ pub(crate) async fn get_protocols_route(
 		protocols: BTreeMap::new(),
 	})
 }
+
+/// # `GET /_matrix/client/unstable/thirdparty/protocols`
+///
+/// Same as `get_protocols_route`, except for some reason Element Android legacy
+/// calls this
+pub(crate) async fn get_protocols_route_unstable(
+	body: Ruma<get_protocols::v3::Request>,
+) -> Result<RumaResponse<get_protocols::v3::Response>> {
+	get_protocols_route(body).await.map(RumaResponse)
+}