Potential fix for failed `test_attribute_slice_seq2seq` on CUDA-enabled platforms

[xuan25]

Description

Potential fix for failed test_attribute_slice_seq2seq on CUDA-enabled platforms

Related Issue

Issue https://github.com/inseq-team/inseq/issues/251

Type of Change

• 🔧 Bug fix (non-breaking change which fixes an issue)

Checklist

• [x] I've read the CODE_OF_CONDUCT.md document.
• [x] I've read the CONTRIBUTING.md guide.
• [x] I've successfully run the style checks using make fix-style.
• [ ] (N/A) I've written tests for all new methods and classes that I created and successfully ran make test.
• [ ] (N/A) I've written the docstring in Google format for all the methods and classes that I used.