Fix pylint warnings (#297)

```
nox > pylint openlifu
************* Module openlifu.db.database
Warning: .nox/pylint/lib/python3.12/site-packages/openlifu/db/database.py:396:24: R1732: Consider using 'with' for resource-allocating operations (consider-using-with)
************* Module openlifu.nav.photoscan
Warning: .nox/pylint/lib/python3.12/site-packages/openlifu/nav/photoscan.py:195:13: I1101: Module 'OpenEXR' has no 'File' member, but source is unavailable. Consider adding this module to extension-pkg-allow-list if you want to perform analysis based on run-time introspection of living objects. (c-extension-no-member)
```

Author: arhowe00

pyproject.toml

@@ -251,6 +251,7 @@ messages_control.disable = [
   "duplicate-code",
   "cyclic-import",
   "unreachable", # This is to allow marking of TODO items with a NotImplementedError
+  "c-extension-no-member",
 ]
 
 [tool.setuptools.package-data]

src/openlifu/db/database.py

@@ -393,9 +393,8 @@ def write_volume(self, subject_id, volume_id, volume_name, volume_data_filepath,
         temp_nifti_path = None
         if is_dicom_file_or_directory(volume_data_filepath):
             self.logger.info(f"Detected DICOM input for volume {volume_id}, converting to NIfTI format")
-            temp_file = tempfile.NamedTemporaryFile(suffix='.nii.gz', delete=False)
-            temp_nifti_path = Path(temp_file.name)
-            temp_file.close()
+            with tempfile.NamedTemporaryFile(suffix='.nii.gz', delete=False) as temp_file:
+                temp_nifti_path = Path(temp_file.name)
 
             try:
                 convert_dicom_to_nifti(volume_data_filepath, temp_nifti_path)