move sphinx to dev requirements

[nitoqq]

sphinx is not required for base functionality, it's only required for docs generation, so it has to be installed separate

[codecov-io]

Codecov Report

Merging #1 (9f0cf16) into master (f62a74e) will not change coverage. The diff coverage is n/a.

@@            Coverage Diff            @@
##            master        #1   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            3         3           
  Lines          112       112           
  Branches        22        22           
=========================================
  Hits           112       112           

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[nitoqq]

Hi, can anybody look at this MR?

[nitoqq-kek]

When it's gonna be merged?