Fix automatic annotation of Active Admin models in migration task

[d1ceward]

This pull request fixes an issue where automatic annotation of Active Admin models was not working with the migration task (cf. auto_annotate.rake), even though the active_admin option was set to true in the :set_annotation_options method.

The fix involves adding the active_admin option to the options variable generated by set_annotation_options(). This variable is then passed to AnnotateModels.do_annotations(), ensuring that the active admin option is set.

Fixes #777

[ctran]

Please add some tests.

[d1ceward]

I understand that you're requesting tests for this change. Unfortunately, I don't know how to test this piece of code because it requires a dummy Rails app and I never done something similar. If you have any tips, please let me know.

In the meantime, I'm confident that my changes are correct because I've carefully tested them manually and because the code is relatively simple.