Disable Travis CI on master
Disable Travis CI on master

This allows Travis to continue running on PRs for release/1.x branches
where we have not enabled GH Actions.

Signed-off-by: Phil Estes <dbac1f450dc8326caa7ba104b384a0eca642250c@linux.vnet.ibm.com>

containerd/containerd,dmcgowan/containerd,mikebrow/containerd,vdemeester/containerd,crosbymichael/containerd,crosbymichael/containerd,dmcgowan/containerd,thaJeztah/containerd,containerd/containerd,estesp/containerd,mikebrow/containerd,estesp/containerd,thaJeztah/containerd,vdemeester/containerd