Bump extern/fabm from cebd56f to 2dac519

Bumps [extern/fabm](https://github.com/fabm-model/fabm-plus) from `cebd56f` to `2dac519`.
- [Commits](fabm-model/fabm-plus@cebd56f...2dac519)

---
updated-dependencies:
- dependency-name: extern/fabm
  dependency-type: direct:production
...

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