Fix failing test on Windows Platform
- test_tokenization_wav2vec2.py failure on Windows - fixed by changing directory separator when running on Windows. 
- tests/test_utils_check_copies.py failure on Windows due to splitting text with "\n" on Windows, instead of "\r\n" - fixed by using universal newlines. 
- tests/extended/test_trainer_ext.py failure on Windows due to "\r" characters encoding issue - fixed by specifying utf-8 encoding. 

Fix for tests in Windows #11586 

Hey @Lynx1820,

Thanks a lot for the PR! Could you run `make style` to make the tests pass? :-)