[BUG] Fix custom timing - does not allow seconds to be inputted

[dmx3377]

Describe the bug
When choosing a custom length of time, seconds cannot be inputted, only whole minutes. (e.g 12:00, but not 12:35, 12:45, etc.)

To Reproduce
Steps to reproduce the behavior:

1. Press 'Set Time'
2. Tap the custom length textbox
3. Input a minute and seconds
4. Observe how seconds are not parsed, and are added to the minutes

Expected behavior
The seconds to be used by the app.

Screenshots
N/A

Additional context
To be fixed.
App still operates as normal, with pre-set lengths of time working.