Bump lib/CPP_PTB from 378dcd8 to 48540ec

Bumps [lib/CPP_PTB](https://github.com/cpp-lln-lab/CPP_PTB) from `378dcd8` to `48540ec`.
- [Release notes](https://github.com/cpp-lln-lab/CPP_PTB/releases)
- [Commits](cpp-lln-lab/CPP_PTB@378dcd8...48540ec)

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

Signed-off-by: dependabot[bot] <support@github.com>