Bump lib/CPP_BIDS from 3b23869 to ad68d19

Bumps [lib/CPP_BIDS](https://github.com/cpp-lln-lab/CPP_BIDS) from `3b23869` to `ad68d19`.
- [Release notes](https://github.com/cpp-lln-lab/CPP_BIDS/releases)
- [Commits](cpp-lln-lab/CPP_BIDS@3b23869...ad68d19)

---
updated-dependencies:
- dependency-name: lib/CPP_BIDS
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]