Fix pytorch conda package name and skip PyPI dependency install on MacOS

Author: matt-graham

.github/workflows/tests.yml

@@ -53,7 +53,7 @@ jobs:
       # by installing torch and healpy using conda
       # https://github.com/healpy/healpy/issues/1012
       run: |
-        conda install jax "jax>=0.3.13,<0.6.0" "numpy>=1.20,<2" ducc0 healpy torch pytest pytest-cov
+        conda install jax "jax>=0.3.13,<0.6.0" "numpy>=1.20,<2" ducc0 healpy pytorch pytest pytest-cov
         python -m pip install --upgrade pip
         pip install --no-deps so3 pyssht
         pip install --no-deps .
@@ -65,7 +65,8 @@ jobs:
         python-version: ${{ matrix.python-version }}
         cache: pip
 
-    - name: Install dependencies
+    - if: matrix.os != 'macos-latest'
+      name: Install dependencies
       run: |
         python -m pip install --upgrade pip
         pip install .[tests]