Random pick never returns the last issue #1100

Bug

In bin/good-first-issue.js the issue selection uses:

const key = cmd.first ? 0 : Math.floor(Math.random() * Math.floor(issues.length - 1))

Because the multiplier is bounded by `issues.length - 1`, `Math.random()` can never produce `issues.length - 1`, so the final issue in the result list is never selectable.

Expected

Every returned issue should have an equal chance of being picked, including the last one.

Fix (one line)

const key = cmd.first ? 0 : Math.floor(Math.random() * issues.length)

The inner `Math.floor(issues.length - 1)` is also redundant since `issues.length` is already an integer.