ci: use --user installs for clean PEP 668 compliance

Author: camille-004

.github/workflows/ci.yml

@@ -106,7 +106,7 @@ jobs:
         uses: actions/checkout@v6
 
       - name: Install lint dependencies
-        run: pip install --no-cache-dir flake8==7.3.0 reuse==5.1.0
+        run: pip install --no-cache-dir --user flake8==7.3.0 reuse==5.1.0
 
       - name: Run flake8
         run: flake8

Dockerfile.ci

@@ -29,10 +29,13 @@ RUN add-apt-repository -y ppa:deadsnakes/ppa && \
 COPY test/requirements.txt /tmp/requirements-test.txt
 COPY docs/requirements.txt /tmp/requirements-docs.txt
 
-RUN pip install --no-cache-dir setuptools wheel build
-RUN pip install --no-cache-dir \
+RUN pip install --no-cache-dir --user setuptools wheel build
+RUN pip install --no-cache-dir --user \
     -r /tmp/requirements-test.txt \
     -r /tmp/requirements-docs.txt
+
+# Add user site-packages to PATH
+ENV PATH="/root/.local/bin:$PATH"
 ENV CUDA_HOME="/usr/local/cuda"
 ENV PATH="$PATH:/usr/local/cuda/bin"
 ENV LD_LIBRARY_PATH="/usr/local/cuda/lib64:${LD_LIBRARY_PATH}"