FEDOT integration test fix

[maypink]

This issue can be resolved with types fixes in GOLEM.
The problem was in types of population before and after mutation: so if one Individual was submitted to the entrance, then the Individual must be returned, otherwise the PopulationT must be returned

[codecov-commenter]

Codecov Report

Merging #161 (96f3961) into main (cf4f45f) will decrease coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #161      +/-   ##
==========================================
- Coverage   73.98%   73.97%   -0.02%     
==========================================
  Files         129      129              
  Lines        7658     7658              
==========================================
- Hits         5666     5665       -1     
- Misses       1992     1993       +1     

Files Changed	Coverage Δ
...olem/core/optimisers/genetic/operators/mutation.py	91.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

[nicl-nno]

Думаю такой фикс в любом случае полезен как обработка граничных ситуаций.

[maypink]

Close since @gkirgizov have already merged the same PR