server/rest: fix new type ambiguity

basically the same as commit eeff085d9d
Will be required once we get to use a newer rustc, at least the
client build for archlinux was broken due to this.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

src/server/rest.rs

@@ -440,7 +440,7 @@ pub async fn handle_api_request<Env: RpcEnvironment, S: 'static + BuildHasher +
             );
             resp.map(|body| {
                 Body::wrap_stream(DeflateEncoder::with_quality(
-                    body.map_err(|err| {
+                    TryStreamExt::map_err(body, |err| {
                         proxmox::io_format_err!("error during compression: {}", err)
                     }),
                     Level::Default,