Check if `Config validator` is working

[decyjphr]

In #604 @paddyroddy commented that they are not able to block adding users to admin role as repository collaborators using the Config Validator in the deployment-settings.yml. This needs to be checked.

To block users getting admin role as collaborators, the following would be set

configvalidators:
  - plugin: collaborators
    error: |
      `Admin cannot be assigned to collaborators`
    script: |
      console.log(`baseConfig ${JSON.stringify(baseconfig)}`)
      return baseconfig.permission != 'admin'

Check if this is still working

[HagegeR]

from what I see here: #378 (comment)
it looks like this is working

[paddyroddy]

from what I see here: #378 (comment) it looks like this is working

I'm not using configvalidators there at the moment