community/libreoffice: upgrade to 7.6.2.1

7.6 will be supported for about as long as 3.19 community/ will be https://wiki.documentfoundation.org/ReleasePlan/7.6

7.5 is soon EOL https://wiki.documentfoundation.org/ReleasePlan/7.5

Also needed to upgrade poppler since our mds is at 2.1.1 !53277 (merged)