`cb` consumes more than it should

[selendym]

Hello.

Currently, the change number of bits command seems to break things, as it will consume every input that has the substring "cb" anywhere within it. This includes all hex numbers that match this, so numbers like 0xcb are impossible to input as regular numbers, though upper case does work.

The problem is most likely here: https://github.com/alt-romes/programmer-calculator/blob/060c9969170e78e9259e801b3bdfa548fdbbb504/src/main.c#L206

As an easy fix, the substring could be changed to something that doesn't clash with anything else, like "bits".

Best regards.