feat: enhance USB backend error handling with specific permission exception

[robberwick]

This pull request includes an important update to the get_attached_blinkstick_devices function in the src/blinkstick/backends/unix_like.py file. The changes improve error handling by adding a try-except block to catch USB errors and provide more specific error messages, and signposting the user towards udev rules as a posible remediation.

Error handling improvements:

• Added a try-except block around the device retrieval logic to catch usb.core.USBError exceptions.
• Included a specific check for "Operation not permitted" errors to raise a more descriptive USBBackendNotAvailable exception when there are permission issues

[Copilot]

Copilot reviewed 1 out of 1 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (2)

src/blinkstick/backends/unix_like.py:72

• [nitpick] The error message could be more informative. Consider adding details on how to add a udev rule or a link to documentation.

"Permission denied accessing USB backend. Does a udev rule need to be added?"

src/blinkstick/backends/unix_like.py:68

• Ensure that the new error handling behavior is covered by tests, specifically for permission issues.

except usb.core.USBError as e: