Bump keras from 3.8.0 to 3.9.0 in /NMSIS/NN/Tests/UnitTest/Scripts

Bumps [keras](https://github.com/keras-team/keras) from 3.8.0 to 3.9.0.
- [Release notes](https://github.com/keras-team/keras/releases)
- [Commits](keras-team/keras@v3.8.0...v3.9.0)

---
updated-dependencies:
- dependency-name: keras
  dependency-version: 3.9.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

NMSIS/NN/Tests/UnitTest/Scripts/requirements.txt

@@ -51,7 +51,7 @@ junit-xml==1.9
 jupyter_client==8.6.2
 jupyter_core==5.7.2
 jupyterlab_widgets==3.0.13
-keras==3.8.0
+keras==3.9.0
 kiwisolver==1.4.7
 libclang==18.1.1
 llvmlite==0.43.0