`c.delta.chat` shows mostly nothing

[r10s]

https://c.delta.chat shows mostly empty pages, maybe related to the current github incident

[Simon-Laux]

can not reproduce, seems to be not an issue anymore

[r10s]

can not reproduce, seems to be not an issue anymore

so eg. https://c.delta.chat/classdc__context__t.html is showing sth to you? i still get an empty page

[link2xt]

I bisected it to commit 0d5d703
This upgraded Doxygen from 1.10.0 to 1.13.2
I tested with 1.11.0, 1.12.0 and 1.13.0, they work. 1.13.1 is the first version that is broken.

[link2xt]

Made a fix: #6876
Generated a new layout with doxygen -l so it uses 2.0 format.