Fix typo

Author: sfodagain

eventstream_rpc/include/aws/eventstreamrpc/EventStreamClient.h

@@ -101,7 +101,7 @@ namespace Aws
             MessageAmendment(const MessageAmendment &lhs);
             MessageAmendment(MessageAmendment &&rhs);
             MessageAmendment &operator=(const MessageAmendment &lhs);
-            MessageAmendment &operator=(const MessageAmendment &&rhs);
+            MessageAmendment &operator=(MessageAmendment &&rhs);
             ~MessageAmendment() noexcept;
             explicit MessageAmendment(Crt::Allocator *allocator = Crt::g_allocator) noexcept;
             MessageAmendment(