Pick a unique artifact filename per runner

This avoids a clash upon upload.

Also remove the isolated build environment when building the wheel,
to ensure that we use Homebrew NumPy < 2.0 (and the one that is linked
to casacore).

.github/workflows/osx.yml

@@ -42,7 +42,7 @@ jobs:
         run: python3 -m venv venv --system-site-packages
 
       - name: Install Python dependencies
-        run: venv/bin/pip install --upgrade pip wheel delocate pytest
+        run: venv/bin/pip install --upgrade pip six wheel delocate pytest
 
       - name: Compile and install python-casacore
         run: venv/bin/pip install .
@@ -51,12 +51,15 @@ jobs:
         run: cd tests && ../venv/bin/pytest
 
       - name: Make binary wheel
-        run: venv/bin/pip wheel -w dist .
+        # XXX Use Homebrew's numpy to be safe for now, especially since
+        # PyPI is now on numpy 2.0, which complicates matters
+        run: venv/bin/pip wheel -w dist --no-build-isolation .
 
       - name: Delocate binary wheel
         run: venv/bin/delocate-wheel -v dist/*.whl
 
       - name: Publish macOS binary wheels
         uses: actions/upload-artifact@v4
         with:
+          name: wheel_${{ matrix.os }}
           path: dist/*.whl