[Enhancement] Make lanms-neo optional

[gaotongxiao]

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Motivation

lanms-neo has long been complained to block the installation on some edge devices, but it is only required by DRRG as of now and removing it from requirements does not seem to make a significant impact in the future.

[codecov]

Codecov Report

Patch coverage: 33.33% and project coverage change: -0.07 ⚠️

Comparison is base (75c06d3) 89.82% compared to head (464d011) 89.76%.

❗ Current head 464d011 differs from pull request most recent head d7f728c. Consider uploading reports for the commit d7f728c to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           dev-1.x    #1772      +/-   ##
===========================================
- Coverage    89.82%   89.76%   -0.07%     
===========================================
  Files          191      191              
  Lines        11218    11228      +10     
  Branches      1582     1584       +2     
===========================================
+ Hits         10077    10079       +2     
- Misses         832      838       +6     
- Partials       309      311       +2     

Flag	Coverage Δ
unittests	89.76% <33.33%> (-0.07%)	⬇️

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Impacted Files	Coverage Δ
mmocr/models/textdet/heads/drrg_head.py	98.83% <33.33%> (-0.78%)	⬇️
...r/models/textdet/module_losses/drrg_module_loss.py	95.89% <33.33%> (-1.33%)	⬇️

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