Update lime.py

[yuzhaouoe]

Convert tensor's dtype to "float" before moving to CPU, which avoids errors when using "bf16"

Description

add .float() before .cpu() to support half precision data type

Checklist

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

[gsarti]

Hi @yuzhaouoe, thanks for opening this PR! Could you provide a minimal code snippet to reproduce the issue with bfloat16 you mention?