bots: Declare fedora-29 image
bots: Declare fedora-29 image

Fedora 29 has forked from Rawhide now [1], so we'll need an image for
this.

[1] https://fedoraproject.org/wiki/Releases/29/Schedule

Closes #9913
moraleslazaro/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,andreasn/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,cockpit-project/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,andreasn/cockpit,cockpituous/cockpit,cockpit-project/cockpit,andreasn/cockpit,moraleslazaro/cockpit,deryni/cockpit,mvollmer/cockpit,garrett/cockpit,andreasn/cockpit,garrett/cockpit,cockpit-project/cockpit,deryni/cockpit,martinpitt/cockpit,mvollmer/cockpit,cockpituous/cockpit,andreasn/cockpit,garrett/cockpit,cockpit-project/cockpit,garrett/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,martinpitt/cockpit,garrett/cockpit,deryni/cockpit,cockpit-project/cockpit,martinpitt/cockpit,deryni/cockpit,deryni/cockpit,cockpituous/cockpit,deryni/cockpit,martinpitt/cockpit,andreasn/cockpit,cockpituous/cockpit,deryni/cockpit,andreasn/cockpit