Check for max PHP version in upgrader

[snipe]

This just tweaks the upgrade script to check for a version of PHP that's too high. While this is documented in the Requirements section of the docs, this should hopefully provide a safeguard or at least more visual feedback to the upgrading.

If it passes (I had an early exit after the version check just to be able to test - it would normally just continue through the upgrader):

If it fails (I had to use a fake max version number here to trigger the fail):

[what-the-diff]

PR Summary

• Introduction of Specific Variable Names
  Certain variables including $required_php_min, $php_min_works, and $php_max_wontwork have been introduced or updated in the upgrade.php file to make the code more explicit and maintainable.
• Improvement of Error Messages
  Errors related to the .env file and PHP version are now communicated more clearly, drastically improving troubleshooting.
• Inclusion of PHP Version Checks
  The script has been modified to check for the appropriate PHP version range using a function called version_compare, leading to better compatibility assurances.
• Additional System Information Display
  For debugging purposes, the script now provides additional information to the user, displaying the current PHP version and the path to the php.ini file in the system. This makes it easier to find potential issues related to PHP configurations.