chore(composer.lock): update twig/*, league/commonmark, nikic/php-parser

Lock file operations: 0 installs, 6 updates, 0 removals
- Upgrading league/commonmark (2.6.0 => 2.6.1)
- Upgrading nikic/php-parser (v5.3.1 => v5.4.0)
- Upgrading twig/extra-bundle (v3.17.0 => v3.18.0)
- Upgrading twig/intl-extra (v3.17.0 => v3.18.0)
- Upgrading twig/markdown-extra (v3.17.0 => v3.18.0)
- Upgrading twig/twig (v3.17.1 => v3.18.0)

league/commonmark updated from 2.6.0 to 2.6.1 patch
- See changes: https://github.com/thephpleague/commonmark/compare/2.6.0...2.6.1
- Release notes: https://github.com/thephpleague/commonmark/releases/tag/2.6.1

nikic/php-parser updated from v5.3.1 to v5.4.0 minor
- See changes: https://github.com/nikic/PHP-Parser/compare/v5.3.1...v5.4.0
- Release notes: https://github.com/nikic/PHP-Parser/releases/tag/v5.4.0

twig/twig updated from v3.17.1 to v3.18.0 minor
   See changes: https://github.com/twigphp/Twig/compare/v3.17.1...v3.18.0
   Release notes: https://github.com/twigphp/Twig/releases/tag/v3.18.0

twig/extra-bundle updated from v3.17.0 to v3.18.0 minor
- See changes: https://github.com/twigphp/twig-extra-bundle/compare/v3.17.0...v3.18.0
- Release notes: https://github.com/twigphp/twig-extra-bundle/releases/tag/v3.18.0

twig/intl-extra updated from v3.17.0 to v3.18.0 minor
- See changes: https://github.com/twigphp/intl-extra/compare/v3.17.0...v3.18.0
- Release notes: https://github.com/twigphp/intl-extra/releases/tag/v3.18.0

twig/markdown-extra updated from v3.17.0 to v3.18.0 minor
- See changes: https://github.com/twigphp/markdown-extra/compare/v3.17.0...v3.18.0
- Release notes: https://github.com/twigphp/markdown-extra/releases/tag/v3.18.0