[RELEASE] Crawler version 9.0.0

 Adds support for TYPO3 9 LTS
 Adds support for TYPO3 10.3
 Drops support for TYPO3 7.6
 Drops support for TYPO3 8.7
 Drops support for  PHP 7.2

For more details check:
https://github.com/AOEpeople/crawler/blob/master/CHANGELOG.mdversion-900