sbcl: remove tohl from meta.maintainers list

Because tohl disappeared (last seen 2021-01-28).

pkgs/development/compilers/sbcl/bootstrap.nix

···
     description = "Lisp compiler";
     homepage = "http://www.sbcl.org";
     license = licenses.publicDomain; # and FreeBSD
-    maintainers = [maintainers.raskin maintainers.tohl];
+    maintainers = [ maintainers.raskin ];
     platforms = attrNames options;
   };
 }