fix link in changelog

Author: kevmoo

pkgs/io/CHANGELOG.md

@@ -86,7 +86,7 @@ main() {
 - Added the `shellSplit()` function, which parses a list of arguments in the
   same manner as [the POSIX shell][what_is_posix_shell].
 
-[what_is_posix_shell]: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/contents.html
+[what_is_posix_shell]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/contents.html
 
 ## 0.2.0