bulk delete hosts does not work with 0.8.0 and foreman 1.22

[hlawatschek]

Describe the bug
after calling a bulk hosts delete action the corresponding tasks fail with the following error:

2019-06-26T17:00:16 [E|bac|] The single-table inheritance mechanism failed to locate the subclass: 'ForemanFogProxmox::Proxmox'. This error is raised because the column 'type' is reserved for storing the class in case of inheritance. Please rename this column if you didn't intend it to be used for storing the inheritance class or overwrite ComputeResource.inheritance_column to use another column for t
hat information. (ActiveRecord::SubclassNotFound)

To Reproduce
bulk delete multiple hosts