Update dependency matplotlib to v3.3.4

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
matplotlib (source)	==3.3.3 -> ==3.3.4

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Release Notes

matplotlib/matplotlib

### [`v3.3.4`](https://togithub.com/matplotlib/matplotlib/releases/v3.3.4) [Compare Source](https://togithub.com/matplotlib/matplotlib/compare/v3.3.3...v3.3.4) This is the fourth bugfix release of the 3.3.x series. This release contains several critical bug-fixes: - Fix WebAgg initialization. - Fix parsing `QT_API` setting with mixed case. - Fix build with link-time optimization disabled in environment. - Fix test compatibility with NumPy 1.20. - Fix test compatibility with pytest 6.2.

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[codecov-io]

Codecov Report

Merging #25 (2926402) into main (3b7cda4) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #25   +/-   ##
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  Coverage   91.89%   91.89%           
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  Files          23       23           
  Lines        1074     1074           
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  Hits          987      987           
  Misses         87       87           

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