Resistor color: Remove unused 'input' field

Hi,

I’ve just completed the Resistor Color exercice and I found that there was an unused field in the cases_test.go file. So I opened a PR to fix it and I got redirected here by a bot.

Screenshot from 2024-03-06 18-24-03

PR is here for reference.

Hi there again.

So I’m not sure who’s approval I should be waiting for to reopen my PR

+cc @andrerfcsantos

Thanks for this! Left just a comment in the PR.