Stable documentation is not most recent release

[gdalle]

The stable docs is for v0.18.8 but the most recent release is 0.18.14. Is there a bug in CI?

[fingolfin]

Indeed the CI setup was quite borked. It should be all set now and once 0.18.21 gets released the "stable" documentation should be updated.

[aviatesk]

This seems to have been fixed.