Update dependency sphinx-rtd-theme to v3

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
sphinx-rtd-theme	~=1.3 → ~=3.1

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Release Notes

readthedocs/sphinx_rtd_theme (sphinx-rtd-theme)

v3.1.0

Compare Source

v3.0.2

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v3.0.1

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v3.0.0

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v2.0.0

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 49.84%. Comparing base (3c64944) to head (a0d41e2).

Additional details and impacted files

@@ Coverage Diff @@## main #478 +/- ##
=======================================
Coverage 49.84% 49.84% =======================================
Files 6 6 Lines 331 331 =======================================
Hits 165 165 Misses 166 166 

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