Force read and write YAML in version 1.1 (#402)
Force read and write YAML in version 1.1 (#402)

`ruamel.yaml` uses version 1.2 by default, and emits version directive
when forced in 1.1 (`%YAML 1.1` header).

`kubectl` doesn't support explicit `%YAML 1.1` header, nor explicit or
even implicit 1.2, at least regarding the boolean literals issue, see
https://github.com/kubernetes/kubernetes/issues/34146

We now force 1.1 on `ruamel.yaml` and disable emitting the `%YAML 1.1`
version directive.

This fixes `'no'` as container env value in the kubernetes manifests.
Deepomatic/dmake,Deepomatic/dmake,Deepomatic/dmake,Deepomatic/dmake