[nemo-media-columns] Fix NameError: name 'gfile' is not defined in update_cb

Description

In nemo-media-columns.py, inside the update_cb method, there is a typo when handling the stopit.TimeoutException exception. The print statement attempts to access gfile.get_uri(), but the parameter passed to update_cb is named file.

This causes a NameError crash when a file processing timeout occurs:

Traceback (most recent call last):
  File ".../nemo-media-columns.py", line 168, in update_cb
    with stopit.ThreadingTimeout(self.timeout):
...
stopit.utils.TimeoutException

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File ".../nemo-media-columns.py", line 171, in update_cb
    print("nemo-media-columns failed to process '%s' within a reasonable amount of time" % (gfile.get_uri(), e))
NameError: name 'gfile' is not defined. Did you mean: 'file'?


Steps to Reproduce
Trigger a timeout during media file processing (e.g., set timeout to a low value or process a large video file that exceeds the timeout threshold).

Observe the terminal output when stopit.TimeoutException is caught.

Expected Behavior
It should log the message using file.get_uri() without raising a NameError.

Proposed Fix
Line 171 in nemo-media-columns/nemo-media-columns.py:
Change gfile.get_uri() to file.get_uri().

Open nemo-media-columns/nemo-media-columns.py and inspect update_cb around line 171, especially the stopit.TimeoutException handler. Trigger or review the timeout path and verify the error message uses the update_cb parameter named file without raising a NameError.