coerce `Hyrax::Permission#mode` to Symbol
coerce `Hyrax::Permission#mode` to Symbol

we always want this value to be a symbol token, so coerce it using the
`dry-types` system.

after discussion in Valkyrie's slack channel, this seems like the right fix.

samvera/hyrax,samvera/hyrax,samvera/hyrax,samvera/hyrax