insert select on conflict do update

[bobrnor]

I fixed an issue when builder does not add on conflict section into insert query with data set instead of slice of records. Test included.

[codecov]

Codecov Report

Merging #55 into master will decrease coverage by 0.1%.
The diff coverage is 40%.

@@            Coverage Diff             @@
##           master      #55      +/-   ##
==========================================
- Coverage   80.48%   80.38%   -0.11%     
==========================================
  Files          17       17              
  Lines        2337     2340       +3     
==========================================
  Hits         1881     1881              
- Misses        349      351       +2     
- Partials      107      108       +1

Impacted Files	Coverage Δ
dataset_insert.go	72.9% <40%> (-1.44%)	⬇️

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[bobrnor]

Hello! Will this merge request would be merged in?