This is the first part of #6846.
Previously, the response schema for list views was an object representing a single item. However, list views return a list of items, and hence it should be an array.
Further work will need to be done to support how pagination classes modify list responses.
There should be no change for views not determined to be list views.
Use of PyYAML's yaml.load function without specifying the Loader
parameter has been deprecated, see https://msg.pyyaml.org/load.
Earlier versions of PyYAML already had the alternative safe_load
function, which limits the loader to a subset of YAML constructs, that
is enough for what we need here.
Fixes#6677
