build/pkgs/gap/spkg-configure.m4: accept >= gap-4.13.0

I've left the upper bound in there, but set to "5.0.0" which should
have no real effect. But if 4.14.0 comes out and breaks somes tests,
it's a lot easier to tweak the existing upper bound than it is to add
one (again) and reindent everything.

build/pkgs/gap/spkg-configure.m4

@@ -2,8 +2,8 @@ SAGE_SPKG_CONFIGURE([gap], [
   # Default to installing the SPKG, if the check is run at all.
   sage_spkg_install_gap=yes
 
-  m4_pushdef([GAP_MINVER],["4.12.2"])
-  m4_pushdef([GAP_LTVER],["4.13.0"])
+  m4_pushdef([GAP_MINVER],["4.13.0"])
+  m4_pushdef([GAP_LTVER],["5.0.0"])
 
   SAGE_SPKG_DEPCHECK([ncurses readline zlib], [
     AC_PATH_PROG(GAP, gap)