Fix sphinx build fail

[sylee957]

References to other Issues or PRs

Fixes #16945

Brief description of what is fixed or changed

Maybe the sphinx had become more strict about having duplicate .. module:: directive.
Using currentmodule instead of module may fix.
https://www.sphinx-doc.org/en/2.0/usage/restructuredtext/domains.html#directive-py:currentmodule

Other comments

Release Notes

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#### References to other Issues or PRs
<!-- If this pull request fixes an issue, write "Fixes #NNNN" in that exact
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Fixes #16945

#### Brief description of what is fixed or changed

Maybe the sphinx had become more strict about having duplicate `.. module::` directive.
Using `currentmodule` instead of module may fix.
https://www.sphinx-doc.org/en/2.0/usage/restructuredtext/domains.html#directive-py:currentmodule 

#### Other comments


#### Release Notes

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[codecov]

Codecov Report

Merging #16948 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master    #16948   +/-   ##
=========================================
  Coverage   73.928%   73.928%           
=========================================
  Files          620       620           
  Lines       160341    160341           
  Branches     37623     37623           
=========================================
  Hits        118538    118538           
- Misses       36310     36313    +3     
+ Partials      5493      5490    -3

[jksuom]

This looks good to me.