Apply small Nextcloud upgrade to 26.0.13

[binarykitchen]

Here's the tested, low-hanging fruit, as communicated in:

• https://github.com/mail-in-a-box/mailinabox/issues/2400
• mailinabox.slack.com/archives/C09E3L9KM/p1718674416382599

Tested and updated the hash checksums. Just a very minor upgrade before we make the next big upgrade ...