fix:is_causal bug

[w-yyh]

test CI

[paddle-bot]

Thanks for your contribution!

[codecov-commenter]

Codecov Report

❌ Patch coverage is 65.21739% with 8 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (develop@e5df9ba). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
paddleformers/transformers/masking_utils.py	58.33%	5 Missing ⚠️
...addleformers/transformers/ernie4_5_moe/modeling.py	25.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             develop    #2932   +/-   ##
==========================================
  Coverage           ?   31.42%           
==========================================
  Files              ?      420           
  Lines              ?    68468           
  Branches           ?        0           
==========================================
  Hits               ?    21519           
  Misses             ?    46949           
  Partials           ?        0           

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