Feature upgrade to typo3 10

UPGRADE.md

 ## Version 7 Breaking Changes
 
-- Dropped TYPO3 8 support
+SignalSlot events has been deprecated and will be removed as soon as TYPO3 9 support is dropped, please use the new
+Event API for your Hooks.
+
+TYPO3 8 is not supported anymore!
+
+The extbase command controller has been migrated to symfony commands. You need to run the upgrade wizard if you used
+the old extbase command in your scheduler.