Add random grayscale

[ternaus]

Fixes: #2080

Summary by Sourcery

Add a new 'RandomGrayscale' transformation to the library, allowing images to be randomly converted to grayscale. Update documentation and tests to include this new feature.

New Features:

• Introduce a new transformation class 'RandomGrayscale' that randomly converts images to grayscale with a specified probability, providing compatibility with torchvision and Kornia APIs.

Documentation:

• Add documentation for the new 'RandomGrayscale' transformation in the README file, including a link to its detailed description.

Tests:

• Include 'RandomGrayscale' in various test cases to ensure its functionality and compatibility with other augmentations.

[sourcery-ai]

Reviewer's Guide by Sourcery

This PR adds a new RandomGrayscale transform class that provides compatibility with torchvision and Kornia APIs by acting as an alias for the existing ToGray transform. The implementation includes comprehensive documentation, test coverage, and necessary updates to export the new transform.

No diagrams generated as the changes look simple and do not need a visual representation.

File-Level Changes

Change	Details	Files
Added new RandomGrayscale transform class as an alias for ToGray	Implemented RandomGrayscale class inheriting from ToGray Added comprehensive docstring with usage examples and references Set default probability to 0.1 to match other libraries Added deprecation warning suggesting direct ToGray usage	albumentations/augmentations/tk/transform.py
Updated test coverage for the new transform	Added RandomGrayscale to various test sets for mask fill value Included in multichannel image augmentation tests Added to float multichannel image tests Added to different channel count tests	tests/test_augmentations.py tests/aug_definitions.py
Updated documentation and exports	Added RandomGrayscale to all exports Added RandomGrayscale to README.md pixel-level transforms list Updated torchvision documentation links for flip transforms	albumentations/augmentations/tk/transform.py README.md

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[sourcery-ai]

Hey @ternaus - I've reviewed your changes and they look great!

Here's what I looked at during the review

• 🟢 General issues: all looks good
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.33%. Comparing base (b1a79c2) to head (9b30139).
Report is 262 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##           main    #2128       +/-   ##
=========================================
+ Coverage      0   90.33%   +90.33%     
=========================================
  Files         0       48       +48     
  Lines         0     7812     +7812     
=========================================
+ Hits          0     7057     +7057     
- Misses        0      755      +755     

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