fix: Fixed expand_line for horizontal & vertical cases

[fg-mindee]

This PR introduces the following modifications:

• fixed expand_line for vertical & horizontal lines
• adds clipping when using float in both frameworks
• added unittests for expand_line

This fixes the randomly failing test we sometimes have on PRs

Any feedback is welcome!

[codecov]

Codecov Report

Merging #842 (93ccf74) into main (0310d6c) will decrease coverage by 0.06%.
The diff coverage is 95.49%.

@@            Coverage Diff             @@
##             main     #842      +/-   ##
==========================================
- Coverage   95.99%   95.93%   -0.07%     
==========================================
  Files         131      131              
  Lines        5042     5086      +44     
==========================================
+ Hits         4840     4879      +39     
- Misses        202      207       +5     

Flag	Coverage Δ
unittests	95.93% <95.49%> (-0.07%)	⬇️

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

Impacted Files	Coverage Δ
doctr/transforms/modules/pytorch.py	94.52% <80.00%> (-3.79%)	⬇️
doctr/transforms/modules/tensorflow.py	92.90% <90.90%> (-0.16%)	⬇️
doctr/transforms/functional/base.py	97.10% <98.14%> (+3.35%)	⬆️
doctr/io/pdf.py	100.00% <100.00%> (+1.66%)	⬆️
doctr/io/reader.py	100.00% <100.00%> (ø)
doctr/transforms/functional/pytorch.py	100.00% <100.00%> (ø)
doctr/transforms/functional/tensorflow.py	100.00% <100.00%> (ø)
doctr/models/_utils.py	97.59% <0.00%> (-1.21%)	⬇️
doctr/transforms/modules/base.py	94.59% <0.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 2581daa...93ccf74. Read the comment docs.

[charlesmindee]

Thanks for this fix!