Remove torchtext

[Eleven1Liu]

What does this PR do?

• Remove torchtext and update related functions (mostly in nn/data_utils.py)

• Dependencies: Remove versions for pytorch (<=2.3.0 for torchtext) and transformers (see PR Upgrade minimum python version from 3.8 to 3.10 #20).

  • Package versions with and without torchtext

  	torch	CUDA	transformers
  with torchtext	<=2.3.0	11.8/12.1	<=4.51.3
  w/o torchtext (this PR)	2.3.0~2.7.1	11.8/12.1/12.6	4.54.0 (tested version)

  • Test results
    ❌ : ERROR: Could not find a version that satisfies the requirement torch==2.x.x (from versions: 2.5.0, 2.5.1, 2.6.0, 2.7.0, 2.7.1), ERROR: No matching distribution found for torch==2.x.x

    cuda	pytorch	python 3.10.18	python 3.13.5
    11.8	2.3.0	✅	❌
    11.8	2.3.1	✅	❌
    11.8	2.4.1	✅	❌
    11.8	2.5.1	✅	✅
    11.8	2.6.0	✅	✅
    11.8	2.7.1	✅	✅
    12.1	2.3.0	✅	❌
    12.1	2.3.1	✅	❌
    12.1	2.4.1	✅	❌
    12.1	2.5.1	✅	✅
    12.6	2.6.0	✅	✅
    12.6	2.7.1	✅	✅

  • torch < 2.3.0 is incompatible with numpy 2.x (note). The error message is as follows:

  A module that was compiled using NumPy 1.x cannot be run in 
  NumPy 2.2.6 as it may crash. To support both 1.x and 2.x
  versions of NumPy, modules must be compiled with NumPy 2.0. 
  Some module may need to rebuild instead e.g. with 'pybind11>=2.12'.
  
  If you are a user of the module, the easiest solution will be to
  downgrade to 'numpy<2' or try to upgrade the affected module.
  We expect that some modules will need time to support NumPy 2.
  

Test CLI & API (bash tests/autotest.sh)

Test APIs used by main.py.

• Test Pass
  • (Copy and paste the last outputted line here.)
• Not Applicable (i.e., the PR does not include API changes.)

Check API Document

If any new APIs are added, please check if the description of the APIs is added to API document.

• API document is updated (linear, nn)
• Not Applicable (i.e., the PR does not include API changes.)

Test quickstart & API (bash tests/docs/test_changed_document.sh)

If any APIs in quickstarts or tutorials are modified, please run this test to check if the current examples can run correctly after the modified APIs are released.