Split lines in secretz solution to get just one md5 per line

The current solution is failing a correct solution since it's getting both md5 values on the first line.
I've added split so it gets one line at a time.
This is how it looks when running stream-adventure verify solution.js, EXPECTED is the old solution, ACTUAL is the solution proposed in this PR:

```
ACTUAL:   "97911dcc607865d621029f6f927c7851 secretz/METADATA.TXT"
EXPECTED: "97911dcc607865d621029f6f927c78512cdcfa9f8bbefb82fb7a894964b5c199 secretz/METADATA.TXT"

ACTUAL:   "2cdcfa9f8bbefb82fb7a894964b5c199 secretz/SPYING.TXT"
EXPECTED: " secretz/SPYING.TXT"

ACTUAL:   ""
EXPECTED: ""

# FAIL

Your solution didn't match the expected output.
Try again, or run `stream-adventure run program.js` to see your solution's output.
```