Fix possible bug in MotionBlur

[huuquan1994]

The current MotionBlur won't work if direction_range is set to -1.0. This is because the create_motion_kernel does not handle that case, resulting in a "near zero" kernel (i.e., kernel with very few non-zero values).
Also, I updated the default value of direction_range to (-0.5, 0.5) to match the description here

I hope that my PR correctly fixes the bug. Thanks!

Summary by Sourcery

Fix the MotionBlur function to handle negative direction values and update the default direction_range for consistency.

Bug Fixes:

• Fix the MotionBlur function to correctly handle negative direction values by adjusting the kernel calculation.

Enhancements:

• Update the default value of direction_range in the MotionBlur transform to (-0.5, 0.5) for consistency with the documentation.

[sourcery-ai]

Reviewer's Guide by Sourcery

The PR fixes a bug in the MotionBlur implementation where negative direction_range values weren't handled correctly, and updates the default direction_range to match the documentation. The fix modifies the motion kernel creation to properly handle negative directions by applying the absolute value for scaling and then negating if needed.

Sequence diagram for create_motion_kernel with negative direction

sequenceDiagram
    participant MotionBlur
    participant create_motion_kernel
    MotionBlur->>create_motion_kernel: Call with direction < 0
    create_motion_kernel->>create_motion_kernel: Calculate t = t * (1 + abs(direction))
    create_motion_kernel->>create_motion_kernel: If direction < 0, t = t * -1
    create_motion_kernel-->>MotionBlur: Return adjusted kernel

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Updated class diagram for MotionBlur

classDiagram
    class MotionBlur {
        - ScaleIntType blur_limit
        - bool allow_shifted
        - tuple< float, float > angle_range
        - tuple< float, float > direction_range
        - bool | None always_apply
        - float p
        + __init__(blur_limit, allow_shifted, angle_range, direction_range, always_apply, p)
    }
    note for MotionBlur "Updated default direction_range to (-0.5, 0.5)"

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File-Level Changes

Change	Details	Files
Modified motion kernel creation logic to handle negative direction values	Added absolute value handling for direction scaling Added conditional negation for negative direction values	albumentations/augmentations/blur/functional.py
Updated default direction_range parameter to match documentation	Changed direction_range default from (-1.0, 1.0) to (-0.5, 0.5)	albumentations/augmentations/blur/transforms.py

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[sourcery-ai]

Hey @huuquan1994 - 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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