Fix negative strides issue in NrrdReader (Project-MONAI#7809)

Fixes Project-MONAI#7798

### Description

Add copy to avoid negative strides when save spatial shape.

### Types of changes
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] Non-breaking change (fix or new feature that would not break
existing functionality).
- [ ] Breaking change (fix or new feature that would cause existing
functionality to change).
- [ ] New tests added to cover the changes.
- [ ] Integration tests passed locally by running `./runtests.sh -f -u
--net --coverage`.
- [ ] Quick tests passed locally by running `./runtests.sh --quick
--unittests --disttests`.
- [ ] In-line docstrings updated.
- [ ] Documentation updated, tested `make html` command in the `docs/`
folder.

Signed-off-by: YunLiu <55491388+KumoLiu@users.noreply.github.com>
Co-authored-by: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>

Author: KumoLiu

monai/data/image_reader.py

@@ -1331,7 +1331,7 @@ def get_data(self, img: NrrdImage | list[NrrdImage]) -> tuple[np.ndarray, dict]:
                 header[MetaKeys.SPACE] = SpaceKeys.LPS  # assuming LPS if not specified
 
             header[MetaKeys.AFFINE] = header[MetaKeys.ORIGINAL_AFFINE].copy()
-            header[MetaKeys.SPATIAL_SHAPE] = header["sizes"]
+            header[MetaKeys.SPATIAL_SHAPE] = header["sizes"].copy()
             [header.pop(k) for k in ("sizes", "space origin", "space directions")]  # rm duplicated data in header
 
             if self.channel_dim is None:  # default to "no_channel" or -1