update problems.json

[Sosuke23]

Place an "x" in the corresponding checkbox if it is done or does not apply to this pull request.

• I have tested my code.
• I have added my solution according to the steps here.
• I have followed the code conventions mentioned here.
  • I understand that if it is clear that I have not attempted to follow these conventions, my PR will be closed.
  • If changes are requested, I will re-request a review after addressing them.
• I have linked this PR to any issues that it closes.

At first, there were only 14 problems in the Custom Comparators and Coordinate Compression module, but the problem counter above was counting 15 because "Wormhole" was included in problem.json but not used as the module's focus problem.