Bump erusev/parsedown-extra from 0.8.1 to 0.9.0 in /_backend

[dependabot]

Bumps erusev/parsedown-extra from 0.8.1 to 0.9.0.

Release notes

Sourced from erusev/parsedown-extra's releases.

0.9.0

This release brings PHP 8.x compatibility and updates the required Parsedown version to 1.8.

Breaking Changes

• Requires Parsedown 1.8.0 or later (previously 1.7.4)
• Requires PHP 7.1 or later

Fixed

• PHP 8.2+ deprecation: replaced mb_convert_encoding(..., 'HTML-ENTITIES') with mb_encode_numericentity() (#192, #173)
• PHP 8.2+ deprecation: replaced 'self::sortFootnotes' callable with [$this, 'sortFootnotes'] (#180)
• PHP 8.4 implicit nullable parameter deprecation in blockSetextHeader (#186)

Changed

• Updated internal element handling to use Parsedown 1.8's element structure (handler/elements arrays instead of text/handler strings)
• Reworked abbreviation insertion to use elementApplyRecursiveDepthFirst instead of regex-replacing rendered HTML
• Reworked footnote back-links to use element arrays instead of string manipulation
• Reworked markup block handling with explicit blockMarkup and blockMarkupContinue methods
• Declared ext-dom, ext-libxml, and ext-mbstring as explicit composer requirements

Infrastructure

• Replaced Travis CI with GitHub Actions
• Tests run on PHP 7.1 through 8.4
• Updated phpunit requirement to ^7.5|^8.5|^9.6

Commits

• 5b5b9b9 Minor cleanups: use https for homepage and add trailing newline
• e0ed978 Bump ParsedownExtra to 0.9.0
• 9e07dd7 Require stable Parsedown 1.8
• 970b8b3 Fix PHP 8.2+ deprecations in ParsedownExtra
• acebd17 Merge pull request #186 from davidbyoung/php-8.4
• b000c29 Removed .idea from .gitignore, updated to use dev-master of Parsedown
• b56e466 Removed debugging step from CI
• 6525d04 Trying to fix CI
• 4d62bd4 Trying to fix CI
• 0c8df84 Trying to fix CI
• Additional commits viewable in compare view

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