Fixup LWG4568: Deal with overfull hbox

Author: eisenwave

source/exec.tex

@@ -5641,7 +5641,8 @@
 namespace std::execution {
   template<class Alloc, @\libconcept{scope_token}@ Token, @\libconcept{sender}@ Sender, class Env>
   struct @\exposidnc{spawn-future-state}@                                                 // \expos
-    : @\exposid{spawn-future-state-base}@<completion_signatures_of_t<@\exposid{future-spawned-sender}@<Sender, Env>, env<>>> {
+    : @\exposid{spawn-future-state-base}@<completion_signatures_of_t<@\exposid{future-spawned-sender}@<Sender, Env>,
+                                                         env<>>> {
     using @\exposidnc{sigs-t}@ =                                                          // \expos
       completion_signatures_of_t<@\exposid{future-spawned-sender}@<Sender, Env>, env<>>;
     using @\exposidnc{receiver-t}@ =                                                      // \expos