9.13.0: PHP 8.6 emitter

• Merged PR #196: Add PHP 8.6 emitter following the availability of
  PHP 8.6 alpha 3, see https://www.php.net/archive/2026.php#2026-07-30-3
  (@thekid)
• Merged PR #195: Emit PHP 8 attributes alongside XP meta information
  (@thekid)