Fix import of BaseFeatureSelectionTransform

[julia-shenshina]

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[codecov-commenter]

Codecov Report

Merging #349 (c4f2360) into master (78b9edc) will decrease coverage by 34.84%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           master     #349       +/-   ##
===========================================
- Coverage   87.37%   52.52%   -34.85%     
===========================================
  Files          96       96               
  Lines        4696     4697        +1     
===========================================
- Hits         4103     2467     -1636     
- Misses        593     2230     +1637     

Impacted Files	Coverage Δ
etna/transforms/__init__.py	100.00% <100.00%> (ø)
etna/commands/__init__.py	0.00% <0.00%> (-100.00%)	⬇️
etna/commands/backtest_command.py	0.00% <0.00%> (-96.43%)	⬇️
etna/commands/forecast_command.py	0.00% <0.00%> (-92.00%)	⬇️
etna/commands/__main__.py	0.00% <0.00%> (-87.50%)	⬇️
etna/commands/resolvers.py	0.00% <0.00%> (-80.00%)	⬇️
etna/analysis/outliers/density_outliers.py	23.91% <0.00%> (-73.92%)	⬇️
etna/transforms/fourier.py	27.08% <0.00%> (-72.92%)	⬇️
etna/transforms/statistics.py	27.50% <0.00%> (-71.67%)	⬇️
etna/transforms/filter.py	28.57% <0.00%> (-71.43%)	⬇️
... and 59 more

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