[TASK] Update Fluid Standalone to 2.6.6

A new fluid standalone version 2.6.6 reverted the changes
that had regressions in v2.6.5 and v2.6.4.

Composer command: composer req typo3fluid/fluid:^2.6.6

Resolves: #89542
Releases: master, 9.5, 8.7
Change-Id: I30a29a3cc07a277bd4a72e83a67a6c3260adc5d7
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/62156


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>