Bump version to 0.5.2dev

[ethanwharris]

What does this PR do?

Fixes # (issue)

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[codecov]

Codecov Report

Merging #898 (d58a48c) into master (78faff0) will decrease coverage by 20.21%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           master     #898       +/-   ##
===========================================
- Coverage   89.08%   68.87%   -20.22%     
===========================================
  Files         230      230               
  Lines       12708    12708               
===========================================
- Hits        11321     8752     -2569     
- Misses       1387     3956     +2569     

Flag	Coverage Δ
unittests	68.87% <100.00%> (-20.22%)	⬇️

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

Impacted Files	Coverage Δ
flash/__about__.py	100.00% <100.00%> (ø)
flash/core/integrations/icevision/transforms.py	13.33% <0.00%> (-80.84%)	⬇️
flash/core/serve/dag/visualize.py	19.04% <0.00%> (-76.20%)	⬇️
flash/core/serve/component.py	21.69% <0.00%> (-72.65%)	⬇️
...ash/pointcloud/segmentation/open3d_ml/backbones.py	20.83% <0.00%> (-70.84%)	⬇️
...lash/image/embedding/vissl/transforms/multicrop.py	27.27% <0.00%> (-69.70%)	⬇️
...lash/image/embedding/vissl/transforms/utilities.py	14.63% <0.00%> (-68.30%)	⬇️
...ash/pointcloud/detection/open3d_ml/data_sources.py	23.93% <0.00%> (-66.67%)	⬇️
flash/image/detection/serialization.py	28.57% <0.00%> (-65.31%)	⬇️
flash/text/question_answering/model.py	26.89% <0.00%> (-64.14%)	⬇️
... and 97 more

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