Bump lib/brain_colours from 68f9a62 to 644749e (cpp-lln-lab#1396)

Bumps [lib/brain_colours](https://github.com/CPernet/brain_colours) from `68f9a62` to `644749e`.
- [Commits](CPernet/brain_colours@68f9a62...644749e)

---
updated-dependencies:
- dependency-name: lib/brain_colours
  dependency-version: 644749e14920b72155c365d062baf214060d6fcc
  dependency-type: direct:production
...

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