T360973: Upgrade composer from 2.6.4 to 2.7.2 | T410453: Upgrade composer to >= 2.9.1
https://getcomposer.org/changelog/2.7.3 PHP 8.4 support
https://getcomposer.org/changelog/2.7.4
https://getcomposer.org/changelog/2.7.5
https://getcomposer.org/changelog/2.7.6
https://getcomposer.org/changelog/2.7.7 Security
https://getcomposer.org/changelog/2.7.8 PHP 8.4 support
https://getcomposer.org/changelog/2.7.9
https://getcomposer.org/changelog/2.8.0
https://getcomposer.org/changelog/2.8.1
Fixes their E_STRICT issues on PHP 8.4 (same as T375707: Avoid E_STRICT in MediaWiki and WMF-deployed extension (Deprecated in PHP 8.4))
Also, the various security issues fixed in 2.7.7 probably warrant updating within 2.7.x for good measure, but might as well go to >= 2.8.1