Upgrade GDAL

[fvankrieken]

GDAL is on 3.8.5

We are currently on my fork of 3.8.3, which was forked due to a bug in null date exporting (see my commit here)

Need to check if this issue is resolved in 3.8.5, and upgrade if so. Would be nice to be getting patches. So todos are roughly

• [ ] see what's new in 3.8.4, 3.8.5 and if we care about these updates
• [ ] see if null date export issue is fixed
• [ ] potentially either just start using 3.8.5, or update my fork if we still need this manual fix

[fvankrieken]

Oops - I made a duplicate of this with #843