[Application] Fix wrong index bug in utils.py for docccano covert

[yaqiangsun]

Fix index bug for doccano convert

Before submitting

• Lint code. If there are lint issues, please format the code first.

# Install and register `pre-commit` in the project folder
pip install pre-commit && pre-commit install

# Process previous code files separately
pre-commit run --file XXXX.py

• Add test cases into tests folder. If there are codecov issues, please add tests cases first.

PR types

Bug fixes

PR changes

Others

Description

Fix wrong index bug.

[paddle-bot]

Thanks for your contribution!

[CLAassistant]

All committers have signed the CLA.

[DrownFish19]

LGTM

[DrownFish19]

Paddle修改导致PaddleNLP历史写法失效，现在已经修改。等待#10364 合入develop分支后拉取最新分支。

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 49.01%. Comparing base (1d5591b) to head (f571226).
Report is 190 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #10361      +/-   ##
===========================================
- Coverage    49.02%   49.01%   -0.01%     
===========================================
  Files          765      765              
  Lines       125879   125879              
===========================================
- Hits         61709    61699      -10     
- Misses       64170    64180      +10     

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[yaqiangsun]

@DrownFish19 @lugimzzz 请帮助Merge该PR

[DrownFish19]

LGTM