[MNT] handle mps backend for lower versions of pytorch and fix `mps…

…` failure on `macOS-latest` runner (#1648)

### Description

This PR handles the issue that may result when setting the device to `mps` if the torch version doesn't support `mps backend` 

Depends on #1633

I used `pytest.MonkeyPatch()` to disable the discovery of the `mps` accelerator. The tests run on CPU for `macOS-latest`

fixes #1596

.github/workflows/test.yml

@@ -79,7 +79,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-13, windows-latest]
+        os: [ubuntu-latest, macos-latest, windows-latest]
         python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
 
     steps:

pytorch_forecasting/utils/_utils.py

@@ -429,7 +429,14 @@ def move_to_device(
         x on targeted device
     """
     if isinstance(device, str):
-        device = torch.device(device)
+        if device == "mps":
+            if hasattr(torch.backends, device):
+                if torch.backends.mps.is_available() and torch.backends.mps.is_built():
+                    device = torch.device("mps")
+                else:
+                    device = torch.device("cpu")
+        else:
+            device = torch.device(device)
     if isinstance(x, dict):
         for name in x.keys():
             x[name] = move_to_device(x[name], device=device)

tests/conftest.py

@@ -69,3 +69,9 @@ def test_dataset(test_data):
         randomize_length=None,
     )
     return training
+
+
+@pytest.fixture(autouse=True)
+def disable_mps(monkeypatch):
+    """Disable MPS for all tests"""
+    monkeypatch.setattr("torch._C._mps_is_available", lambda: False)