Fixed checkout_date for licenses on print all assigned for users

[snipe]

This fixes an issue where the updated_at date was not being included in the user->license relationship, so the checkout date was not being included in the "print all assigned". This acts a little different because of the (dumb) way we handle the license joins right now, where the join entry gets created, but it actually matters when it's updated, since the join record can exist unassigned.

[shortcut-integration]

This pull request has been linked to Shortcut Story #25019: Checkout date not consistently showing on print all assigned form.

[what-the-diff]

PR Summary

• Addition of Timestamps to 'licenses' method in the 'User' Model
  The method for handling licenses within the User model has been enhanced. It now includes 'created_at' and 'updated_at' timestamps. These fields will provide more information about when the license was created and last updated.

• Display of 'updated_at' Timestamp in 'print.blade.php' View
  The 'updated_at' timestamp from the 'pivot' table is now shown in the 'print.blade.php' view for each license. This allows users to easily see when a specific license was last updated.