🐛 FIX: Fix RemovedInSphinx10Warning for inventory item iteration

Fixes the deprecation warning from Sphinx >= 8.2:

```
RemovedInSphinx10Warning: The iter() interface for _InventoryItem objects is deprecated.
Please access the `project_name`, `project_version`, `uri`, and `displayname` attributes directly.
```

The previous code unpacked `_InventoryItem` as a tuple (`project, version, loc, text = data[target]`), which triggers the warning.

This uses `hasattr` to detect whether the new attribute-based API is available and falls back to tuple unpacking for older Sphinx versions. This approach is more robust than version checking (cf. #1079 which used `sphinx.__version_info__` — an attribute that doesn't exist; the correct attribute is `sphinx.version_info`).

Note: the correct attribute name on `_InventoryItem` is `display_name` (with underscore), despite the warning message saying `displayname`.

Author: chrisjsewell

myst_parser/inventory.py

@@ -366,7 +366,15 @@ def filter_sphinx_inventories(
                 continue
             for target in data:
                 if match_with_wildcard(target, targets):
-                    project, version, loc, text = data[target]
+                    data_target = data[target]
+                    if hasattr(data_target, "project_name"):
+                        # Sphinx >= 8.2
+                        project = data_target.project_name
+                        version = data_target.project_version
+                        loc = data_target.uri
+                        text = data_target.display_name
+                    else:
+                        project, version, loc, text = data_target
                     yield (
                         InvMatch(
                             inv=inv_name,