v3.3.1

@david-cortes

Changes

[python][sklearn] Allow non-serializable objects in callbacks argument @StrikerRUS (#4723)
Fix ASAN issues with std::function usage @david-cortes (#4673)
fix behavior for default objective and metric @StrikerRUS (#4660)

[docs] Add Tong Wu and Zhiyuan He as code owners @shiyu1994 (#4717)
[docs] fix R API link to point to the current version of docs @StrikerRUS (#4691)
[docs] update comment about pre-installed Java version for SWIG build @StrikerRUS (#4710)
[docs] fix C API docs rendering @StrikerRUS (#4688)
[docs] Add avatar to Yu Shi in R docs @StrikerRUS (#4690)

release v3.3.1 @jameslamb (#4715)
[ci] introduce CI jobs that mimic CRAN gcc-ASAN and clang-ASAN tests (fixes #4674) @jameslamb (#4678)
[R-package][test] add reference to the original issue in R-package test @StrikerRUS (#4720)
[python] Improve error message for plot_metric with Booster @js850 (#4709)
[R-package] allow for small numerical differences in Booster test @jameslamb (#4714)
Fix some paramater hints when loading from binary file @hzy46 (#4701)
[ci] fix CI Windows script to use downloaded SWIG, not the pre-installed one @StrikerRUS (#4711)
[ci] Rename RTD config file @StrikerRUS (#4689)
[ci] Bump Google Test version from 1.10.0 to 1.11.0 @StrikerRUS (#4683)
[python] fix mypy error in engine.py @rakki-18 (#4675)
[python] fix mypy error in setup.py @rakki-18 (#4671)
update Guolin's e-mail in setup.py @StrikerRUS (#4663)
Replace deprecated licenseUrl field with license one in .nuspec file @StrikerRUS (#4669)
[python][sklearn] use __sklearn_is_fitted__() in all estimator fitness checks @StrikerRUS (#4654)
[ci] Bump version for development @StrikerRUS (#4662)