switch to use ruamel.yaml

[fruch]

since ruamel.yaml can preserve yaml comment so we can have the original yaml files of scylla

[fruch]

i'd say it's one of steps to migrate our CI/CD from yaml to ruamel.yaml. what if the trial failed, shall we revert the changes? i don't know =)

yes we can, but this change on it's own shouldn't be breaking anything (as far as I know) i.e. I did tested it with dtest (and it was passing CCM CI tests)

if it proven to causing issue, we'll consider/handle it as in any other change.

and every trial, start with one small step, this PR is small enough :)

[cezarmoise]

maybe the readme needs to be updated as well https://github.com/scylladb/scylla-ccm/blob/076a4068c879da661cdda5df0e623a211e5b7282/README.md?plain=1#L59

[fruch]

maybe the readme needs to be updated as well

https://github.com/scylladb/scylla-ccm/blob/076a4068c879da661cdda5df0e623a211e5b7282/README.md?plain=1#L59

that readme probably need rewriting anyhow, I touch it about in that requirement section, which is mostly isn't needed anymore now

those are from days you could install ccm as a package, now you can and it's requirements are set inside setup.py