Add Hugging Face demo shield

[osanseviero]

As suggested in #492 (comment)

[fg-mindee]

Thanks a lot Omar 🙏

[codecov]

Codecov Report

Merging #501 (93c9595) into main (3b2d375) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #501      +/-   ##
==========================================
- Coverage   51.09%   51.07%   -0.03%     
==========================================
  Files         109      109              
  Lines        4188     4188              
==========================================
- Hits         2140     2139       -1     
- Misses       2048     2049       +1     

Flag	Coverage Δ
unittests	51.07% <ø> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
doctr/models/_utils.py	28.57% <0.00%> (-1.20%)	⬇️

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[fg-mindee]

Hi @osanseviero 👋

Following up on #543, the demo deployed on HF Spaces is failing and should be updated 😅
Is there a way to add me as a contributor so that you don't have to do those updates yourself on HF Spaces?

Best!