feat: Improved all model checkpoints and added HF hub loading function

[frgfm]

This PR introduces the following modifications:

• updates all model checkpoints
• adds their performance evaluation on OpenFire in a CSV
• adds a model_from_hf_hub function that instantiates the model & load the parameters from the name of the HF hub repo
• adds entry in the documentation & unittests

Closes #123

Any feedback is welcome!

[codecov]

Codecov Report

Merging #159 (9442e99) into master (a3a73e5) will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #159      +/-   ##
==========================================
+ Coverage   93.83%   93.88%   +0.04%     
==========================================
  Files           8        9       +1     
  Lines         211      229      +18     
==========================================
+ Hits          198      215      +17     
- Misses         13       14       +1     

Flag	Coverage Δ
unittests	93.88% <100.00%> (+0.04%)	⬆️

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

Impacted Files	Coverage Δ
pyrovision/models/mobilenetv3.py	100.00% <100.00%> (ø)
pyrovision/models/resnet.py	100.00% <100.00%> (ø)
pyrovision/models/rexnet.py	100.00% <100.00%> (ø)
pyrovision/models/utils.py	100.00% <100.00%> (ø)
pyrovision/datasets/utils.py	88.73% <0.00%> (-1.41%)	⬇️

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