Add --break-system-packages to CI pip installs

Ubuntu 24.04 ships a PEP 668 externally-managed Python where system-wide
pip installs are blocked unless the flag is set, even from a sudo
shell. Required after the runner bump.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: Dobiasd

.github/workflows/ci.yml

@@ -12,8 +12,8 @@ jobs:
           # system libs
           sudo apt-get install libblas-dev liblapack-dev libatlas-base-dev gfortran
           # python libs
-          sudo pip3 install --upgrade pip
-          sudo pip3 install numpy scipy h5py "tensorflow==2.21.0" "keras==3.14.0"
+          sudo pip3 install --break-system-packages --upgrade pip
+          sudo pip3 install --break-system-packages numpy scipy h5py "tensorflow==2.21.0" "keras==3.14.0"
           echo "Python version:"
           python3 --version
           echo "Version numbers of TensorFlow and Keras:"