I'm using Zola and Cloudflare Pages, and it is currently possibly to use ZOLA_VERSION=0.17.1. I thought I had opted into the Pages v2 beta (I remember joining a Discord for this purpose a while ago), but on the actual page the setting is at v1.
You can change this under Settings > Builds & deployments > Build system version. Cheers!
Apparently you can now ZOLA_VERSION to _any_ version you desire in v1 and the build system will install it on demand. I didn't realize that part had changed.
On the other hand, v2 doesn't even have Zola; my builds failed with a "failed to find zola command".
I guess we're now set for life, and will never have to wait for Cloudflare to update the image in order to bump the version. Less headaches for everyone.
You can change this under Settings > Builds & deployments > Build system version. Cheers!