Fix macOS CI failure: replace mamba with pip in build-linux job

[Copilot]

libmamba fails to codesign libffi on macOS GitHub Actions runners (Could not codesign executable: Broken pipe), causing all build-linux (macos-latest, *) matrix jobs to fail.

Changes

• .github/workflows/build-test-conda.yml: In the build-linux job, replace conda-incubator/setup-miniconda + mamba install with actions/setup-python@v5 + pip install
  • All dependencies (numpy scipy h5py pandas xarray hatchling tqdm) are available on PyPI with pre-built wheels for both Linux and macOS — conda is unnecessary here
  • The test job (Ubuntu-only) is unchanged

Before:

- name: Set up Python
  uses: conda-incubator/setup-miniconda@v3
  with:
    python-version: ${{ matrix.python-version }}
    mamba-version: "*"
    channels: conda-forge
- name: Install dependencies
  run: |
    mamba install numpy scipy h5py pandas xarray hatchling tqdm
    python -m pip install --upgrade pip
    pip install .

After:

- name: Set up Python
  uses: actions/setup-python@v5
  with:
    python-version: ${{ matrix.python-version }}
- name: Install dependencies
  run: |
    python -m pip install --upgrade pip
    pip install numpy scipy h5py pandas xarray hatchling tqdm
    pip install .

[Copilot]

Pull request overview

This PR updates the CI workflow to avoid conda/mamba in the build-linux matrix job (which also runs on macos-latest) by switching to actions/setup-python and installing dependencies via pip, addressing macOS failures caused by libmamba codesigning.

Changes:

• Replaced conda-incubator/setup-miniconda + mamba install with actions/setup-python@v5 + pip install in the build-linux job.
• Kept the Ubuntu-only test job unchanged.

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