Use Python venv

Author: franzpoeschel

.github/workflows/macos.yml

@@ -53,7 +53,9 @@ jobs:
       env: {MACOSX_DEPLOYMENT_TARGET: 11.0}
       run: |
         set +e
-        brew install numpy pandas
+        python -m venv env
+        source env/bin/activate
+        python -m pip install numpy pandas
         set -e
     - name: Build
       env: {CXXFLAGS: -Werror, MACOSX_DEPLOYMENT_TARGET: 11.0}
@@ -63,6 +65,7 @@ jobs:
       # 11.0+ for arm64/aarch64 (M1/M2) builds
       run: |
         share/openPMD/download_samples.sh build
+        source env/bin/activate
         cmake -S . -B build \
           -DopenPMD_USE_PYTHON=ON  \
           -DopenPMD_USE_MPI=OFF    \