Incorrect display/calculation of the grade graph

[Th3Ph4nt0m]

General Troubleshooting

• [x] I have checked for similar issues.
• [x] I have updated to the latest version.
• [x] I have checked the branches or the maintainers' PRs for upcoming fixes.

Describe the bug

The grade curve is rounded, which ensures that the display is consumed. For example, it looks like you had a 1+. Also, the curve goes out of the box at the bottom.

Screenshots

Graph

Environment:

• Device model: Samsung Tab S7
• OS version: Android Q
• App version: 10.3.2

[Th3Ph4nt0m]

May be related to #139