[nfc] fix dim not defined and fix typo

[digger-yu]

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📝 What does this PR do?

1. fix dim not defined
2. fix typo
   Make code easier to read
   modified: applications/Chat/evaluate/gpt_evaluate.py
   modified: applications/Chat/evaluate/unieval/evaluator.py
   modified: applications/Chat/evaluate/unieval/utils.py
   modified: applications/Chat/tests/test_data.py

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