Fixed issue with completed weeks (#702)

[BicaniWolfie]

Description

Fixed bug where a current week plan would be added to "Overståede uger" if the week crosses into the new year. The issue occurred when a week's number is the same on both sides of the New Year, for example a week starting on the 29th of December and ending on the 4th of January the following year. The issue was fixed by adding more checks for cases where the error might occur.

Fixes #702

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

The code has been tested independently of any mobile platform, where the tests were ran using Visual Studio Code

• Flutter version: 3.3.8
• Dart version: 2.18.4

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas, if necessary
• I have made corresponding changes to the documentation, if necessary
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works, if necessary
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have Acceptance Tested this on an iOS device
• I have Acceptance Tested this on an Android device