ci/conda: fix for ARM64

See conda-incubator/setup-miniconda#312 for details

Author: jcarpent

Diff for: .github/workflows/macos-linux-conda.yml

@@ -49,13 +49,24 @@ jobs:
         restore-keys: ccache-macos-linux-conda-${{ matrix.os }}-${{ matrix.build_type }}-${{ matrix.cxx_options }}-${{ matrix.python-version }}-
 
     - uses: conda-incubator/setup-miniconda@v3
+      if: matrix.os != 'macos-14'
       with:
         activate-environment: eigenpy
         auto-update-conda: true
         environment-file: .github/workflows/conda/environment_macos_linux.yml
         python-version: ${{ matrix.python-version }}
         auto-activate-base: false
 
+    - uses: conda-incubator/setup-miniconda@v3
+      if: matrix.os == 'macos-14'
+      with:
+        activate-environment: eigenpy
+        auto-update-conda: true
+        environment-file: .github/workflows/conda/environment_macos_linux.yml
+        python-version: ${{ matrix.python-version }}
+        auto-activate-base: false
+        installer-url: https://github.com/conda-forge/miniforge/releases/download/23.11.0-0/Mambaforge-23.11.0-0-MacOSX-arm64.sh
+
     - name: Build EigenPy
       shell: bash -el {0}
       run: |