Greenkeeper tried to downgrade a dependency

[Kinrany]

My project is on rollup@^1.27.0. Greenkeeper pinned rollup to 1.26.5 and complained that CI checks (which include npm ci) didn't pass.

Kinrany/template#4

[Kinrany]

Looks like I was only able to see this issue thanks to #981. Otherwise it would happily check the downgraded version and delete the branch without notifying anyone.