The current pgadmin4.sh label default to x86_64 when a arm64 version is also available.

I also introduces those other changes:

• downloadParent url updated to use the same between version fetching and dmg fetching
• update regex to use \d instead of [0-9]
• update sort param from -V to --sort-version to be more explicit

This is my first PR - please let me know if this is the correct way to fix this issue.

Tested on my local (arm64)