feat: ✨ allow beam width > 1 in the CRNN postprocessor

[khalidMindee]

This PR aims to allow beam search decoding in CRNN postprocessing , instead of only greedy decoding ( corresponding to a beam search with beam width equal to 1 )

[codecov]

Codecov Report

Merging #630 (8d4a8c1) into main (b85d8c8) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head 8d4a8c1 differs from pull request most recent head 5aeb02d. Consider uploading reports for the commit 5aeb02d to get more accurate results

@@           Coverage Diff           @@
##             main     #630   +/-   ##
=======================================
  Coverage   94.92%   94.93%           
=======================================
  Files         133      133           
  Lines        5281     5288    +7     
=======================================
+ Hits         5013     5020    +7     
  Misses        268      268           

Flag	Coverage Δ
unittests	94.93% <100.00%> (+<0.01%)	⬆️

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Impacted Files	Coverage Δ
doctr/models/recognition/crnn/tensorflow.py	100.00% <100.00%> (ø)
doctr/transforms/modules/base.py	94.59% <0.00%> (ø)

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[khalidMindee]

This PR solves #602 for exporting CRNN recognition models as saved models .

[charlesmindee]

Thanks for this feature, but we may want to keep the same input/output format to avoid breaking the predictors

[fg-mindee]

As Charles mentioned, there are some parts of this PR that could be integrated and others that introduce breaking changes, that cannot be handled right now :/

I think we should split this into 2 PRs:

• one to fix SavedModel compatibility
• one to add topk

[fharper]

@khalidMindee is this PR still good? If yes, can you review FG's & @charlesmindee comments, modify in consequences so we can potentially merge it please?

[khalidMindee]

This PR has been updated accordingly to keep only allowing beam width , postponning the fix for exporting the saved model as it introduces a breaking change due to signature change

[charlesmindee]

Thanks!

[github-actions]

Hey @charlesmindee 👋
You merged this PR, but it is not correctly labeled. The list of valid labels is available at https://github.com/mindee/doctr/blob/main/.github/verify_pr_labels.py

[frgfm]

Missing two labels "module: models" and "ext: test" I think @charlesmindee :)