[BUGFIX] Require symfony/polyfill-php80 at least in version 1.16.0

Used commands:

    composer require symfony/polyfill-php80:^1.16
    composer require symfony/polyfill-php80:^1.16 \
        -d typo3/sysext/form --no-update

This fixes a composer min acceptance test failure, that chokes on the
function str_ends_with() not being available in a PHP 7.4 environment.

Resolves: #95110
Releases: master
Change-Id: I54d410adc7ad813dc3c840c4292ee9ec3df6f76c
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/70894


Tested-by: core-ci <typo3@b13.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>