10.0.0: PHP 7.4+

• Heads up: Dropped support for PHP < 7.4, see xp-framework/rfc#343
  (@thekid)
• Added PHP 8.5 to test matrix - @thekid
• Refactored template loading to no longer use deprecated functionality
  from the xp-forge/mustache library, making it compatible with its
  newest major release
  (@thekid)