Save current notebook as part of ottr::export()

[dbroockman]

Is your feature request related to a problem? Please describe.
When students run ottr::export(), it creates a Zip file of the last saved version of the notebook, which might be out of date. Even though I tell students to manually save before running export, many forget to do so.

Describe the solution you'd like
When ottr::export() runs, have it save the current version of the notebook first.

Describe alternatives you've considered
I've told students to manually save first, but many forget.

Additional context
Many students then complain about their grades being wrong because the last answer or two doesn't show up.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[chrispyles]

Opened ucbds-infra/ottr#20 which will be included in the next version of ottr.

After this is available, Otter Assign will need to be updated to pass the argument when applicable.

[chrispyles]

This is included in ottr v1.4.0 which is on it's way to CRAN.