[exec.sysctxrepl.query] Use \exposconcept for class-type (#8166)

Author: hewillk

source/exec.tex

@@ -8459,7 +8459,7 @@
     virtual void set_error(exception_ptr) noexcept = 0;
     virtual void set_stopped() noexcept = 0;
 
-    template<class P, @\exposid{class-type}@ Query>
+    template<class P, @\exposconcept{class-type}@ Query>
       optional<P> try_query(Query q) noexcept;
   };