⬆️ Update brainunit requirement from <=0.0.4 to <=0.0.8

---
updated-dependencies:
- dependency-name: brainunit
  dependency-version: 0.0.8
  dependency-type: direct:development
...

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

Author: dependabot[bot]

requirements-dev.txt

@@ -5,7 +5,7 @@ absl-py<=2.1.0
 brainstate<=0.1.0.post20241210
 braintaichi<=0.0.4
 braintools<=0.0.4.post20241215
-brainunit<=0.0.4
+brainunit<=0.0.8
 colorama<=0.4.6
 contourpy<=1.3.1
 cycler<=0.12.1