[Bug]: The `get-architectures` job fails on projects that uses a string array in the architectures[].build-on property

[brlin-tw]

What happened?

The following configuration:

architectures:
  - build-on: [amd64]

triggered the following error:

 Error: csv encoding only works for arrays of scalars (string/numbers/booleans), child[0] is a !!seq

What should have happened?

According to the documentation both data types should be supported.