gluon-core: allow v4 nameservers in the mesh

Signed-off-by: Jan Luebbe <jlu@pengutronix.de>

Author: jluebbe

package/gluon-core/check_site.lua

@@ -65,7 +65,7 @@ end
 need_boolean(in_site({'poe_passthrough'}), false)
 
 if need_table({'dns'}, nil, false) then
-	need_string_array_match({'dns', 'servers'}, '^[%x:]+$')
+	need_string_array_match({'dns', 'servers'}, '^[%x:.]+$')
 	need_number({'dns', 'cacheentries'}, false)
 end