A submitted homework that was marked "not done" can't be marked as done again.

[Jonas-Sander]

Describe the bug

A homework with a submission that was sucessfully submitted, then marked as "not done" and then marked as done again can't be marked as done again.

Steps to Reproduce

(See video below)

1. Go to homework page
2. Create a new homework with submissions
3. Go to the submission page of the homework
4. Upload a file
5. Submit the homework.
6. Go to the homework page
7. Switch to the done / completed homeworks tab
8. Tap onto the homework from above
9. Tap onto "mark as not done / not completed" at the bottom of the page
10. Go to the not done / not completed homeworks tab
11. Tap onto the homework from above
12. (see below)

Current broken behavior

1. The button at the bottom of the page says "mark as not done / not completed" even though the homework was already marked as not completed and appears on the not completed homework tab.
2. If the button is pressed the homework does not get marked as done (i.e. the homework can never be marked as completed again).

Expected behavior

1. The button at the bottom of the page should say "mark as done / completed".
2. If pressed the homework should be marked as completed and appear in the completed homeworks tab.

Screenshots, videos or logs

https://user-images.githubusercontent.com/29028262/151866267-9d858782-053f-4468-b758-b00b8b5b6a40.mp4

Tested device

• Device: Pixel 4a
• OS: Android 12
• App version: 1.6.1 (315)

Original Issue: https://gitlab.com/codingbrain/sharezone/sharezone-app/-/issues/1426