1. All exercises should print a trailing \n
2. The build script should always show you _exactly_ what it's looking
for when you get it wrong. Therefore, .output should be set to the
exact expected output.
When I hit 999 exercises, I will finally have reached the ultimate
state of soteriological release and no more exercises will be needed.
The cycle will be complete. All that will be left is perfect quietude,
freedom, and highest happiness.
A plain `zig build` was exiting as expected after the version check
failure did an early 'return'.
But `zig build 01` (specifying a step) would print the fail message
and then continue...but fail to find the step (which was not added).
Calling `exit()` solves this. Calling it with an error status code
causes vomiting in the build system (since, you know, there was an
error). So returning with `exit(0)` is the way to go here.