[janezd]

Description of changes

Add a migration helper and a test that will remind us to use it (after we release orange-widget-base and require the new version).

Includes

• Code changes

[codecov-commenter]

Codecov Report

❌ Patch coverage is 33.33333% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.04%. Comparing base (47f8d03) to head (46badcb).
⚠️ Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
orangewidget/utils/filedialogs.py	33.33%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #299      +/-   ##
==========================================
- Coverage   73.07%   73.04%   -0.03%     
==========================================
  Files          34       34              
  Lines        9240     9246       +6     
==========================================
+ Hits         6752     6754       +2     
- Misses       2488     2492       +4     

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