Move static folder

[bwheelz36]

this turned out to be a lot more work/ changes than I expected...

• Fixes Move static inside docsrc #467
• Updates the build_docs CI job to use pyproject.toml and poetry
• also added a link to the scikit learn docs on different GP kernels to advanced tour notebook

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.68%. Comparing base (c7e5c39) to head (b032feb).
Report is 4 commits behind head on master.

❗ Current head b032feb differs from pull request most recent head 63b281b

Please upload reports for the commit 63b281b to get more accurate results.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #485      +/-   ##
==========================================
- Coverage   94.91%   94.68%   -0.24%     
==========================================
  Files           9        9              
  Lines         669      677       +8     
==========================================
+ Hits          635      641       +6     
- Misses         34       36       +2     

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