Add testcase for TestCalculateResellPrice

[jesse-kroon]

I've described the issue here.
https://forum.exercism.org/t/expanding-test-cases-for-vehicle-purchase-exercise-in-the-go-track/9066

(Agreed by @andrerfcsantos on Exercism Community)

[github-actions]

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[iHiD]

@andrerfcsantos can we merge this with [no important files changed] pls (or whatever the correct magic string is. I don't think we need to rerun all the existing solutions for this change.

[andrerfcsantos]

Thanks for this!