chore: drop go1.13

[ubogdan]

Describe the PR
Drop support for go1.13

Relation issue
NONE.

Additional context
None

[codecov]

Codecov Report

Merging #190 (8aba36e) into master (74c905c) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #190   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines           91        91           
=========================================
  Hits            91        91           

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