[BUGFIX] Sort upgrade documentation by filename

Restore sorting of documentation files based on their filename
like it was available up to TYPO3 version 8.7.

Resolves: #87390
Releases: master, 9.5
Change-Id: I2ab75d6b750b3a3003f00ed174c0d3dfb865bec9
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63913


Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Susanne Moog <look@susi.dev>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Susanne Moog <look@susi.dev>