Fix that segment is string

[Mr-Geekman]

IMPORTANT: Please do not create a Pull Request without creating an issue first.

Before submitting (must do checklist)

• Did you read the contribution guide?
• Did you update the docs? We use Numpy format for all the methods and classes.
• Did you write any new necessary tests?
• Did you update the CHANGELOG?

Type of Change

• Examples / docs / tutorials / contributors update
• Bug fix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves an existing feature)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Proposed Changes

Look #568.

Related Issue

#568.

Closing issues

Closes #568.

[codecov-commenter]

Codecov Report

Merging #602 (54c2d05) into master (a321f5a) will decrease coverage by 0.19%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #602      +/-   ##
==========================================
- Coverage   85.35%   85.15%   -0.20%     
==========================================
  Files         117      117              
  Lines        5789     5813      +24     
==========================================
+ Hits         4941     4950       +9     
- Misses        848      863      +15     

Impacted Files	Coverage Δ
etna/analysis/eda_utils.py	18.51% <ø> (-0.60%)	⬇️
etna/datasets/tsdataset.py	90.05% <100.00%> (+0.22%)	⬆️
etna/analysis/plotters.py	16.35% <0.00%> (-0.45%)	⬇️
etna/analysis/__init__.py	100.00% <0.00%> (ø)

📣 Codecov can now indicate which changes are the most critical in Pull Requests. Learn more