Erdős Problem 742: status mismatch (repo=open, erdosproblems.com=solved)

The status of [Erdős problem 742](https://www.erdosproblems.com/742) appears to have changed.

- **[This repo](http://github.com/google-deepmind/formal-conjectures/blob/main/FormalConjectures/ErdosProblems/742.lean)**: `open` (in `FormalConjectures/ErdosProblems/742.lean`)
- **[erdosproblems.com/742](https://www.erdosproblems.com/742)**: `solved`

Please verify and update the `@[category research ...]` annotation if appropriate.

Inspect FormalConjectures/ErdosProblems/742.lean and compare its current research-status annotation with the status shown at erdosproblems.com/742. Verify whether the problem is solved, update the annotation if appropriate, and confirm the file remains valid.

Written by the indexing model from the issue text.