As I understand your issue, Follow the below solution:

The latest version of "doctrine/doctrine-fixtures-bundle" is not compatible with UVdesk. As this release came in the last week.

You can fixed this issue by changing the version in composer.json in uvdesk:

"doctrine/doctrine-fixtures-bundle": "^3.4", **TO** "doctrine/doctrine-fixtures-bundle": "3.4.1",

After Updating the changes in composer.json. Simply, run the composer update command in your project root directory.

I Hope, This will resolve your issue.