Bump lib/spm_2_bids from 6e1f5dd to bce6800 (#1196)

Bumps [lib/spm_2_bids](https://github.com/cpp-lln-lab/spm_2_bids) from `6e1f5dd` to `bce6800`.
- [Release notes](https://github.com/cpp-lln-lab/spm_2_bids/releases)
- [Commits](cpp-lln-lab/spm_2_bids@6e1f5dd...bce6800)

---
updated-dependencies:
- dependency-name: lib/spm_2_bids
  dependency-type: direct:production
...

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