⬆️ bump brainunit from 0.2.1 to 0.2.2 (#84)

Bumps [brainunit](https://github.com/chaobrain/brainunit) from 0.2.1 to 0.2.2.
- [Release notes](https://github.com/chaobrain/brainunit/releases)
- [Commits](https://github.com/chaobrain/brainunit/commits)

---
updated-dependencies:
- dependency-name: brainunit
  dependency-version: 0.2.2
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

requirements.txt

@@ -1,5 +1,5 @@
 # infrastructure packages
-brainunit==0.2.1
+brainunit==0.2.2
 brainevent==0.0.7
 brainstate==0.3.0
 braintools==0.1.8