fixed bug where non-jpg document derivatives fail

[gwiedeman]

Before, in the documents processor, files would open from /tmp as a string, and then fail during IO.copy_stream in Hyrax here: https://github.com/samvera/hyrax/blob/master/app/services/hyrax/persist_derivatives.rb#L13

Now, it opens them as binary and works as intended.

[cjcolvar]

@gwiedeman The Renaming Branch Working Group is in the process of renaming the default branch from master to main in Samvera and Samvera-Labs repos. This brings repositories into compliance with the Samvera Community Code of Conduct (https://samvera.atlassian.net/wiki/spaces/samvera/pages/405212316/Code+of+Conduct) and language recommendations (https://github.com/samvera/maintenance/blob/master/templates/CONTRIBUTING.md#language). Background on the renaming effort is available in the working group notes (https://samvera.atlassian.net/wiki/x/b5IYHg).

I just updated the default branch name for hydra-derivatives which had the side effect of closing your pull request. Please reopen this pull request targeting the main branch if it is still relevant. Thanks!