GitLab

* [ci] fix GPG key download for R Linux jobs

* force use of the new config file

* empty commit

* enforce dask version to be >=2023.5.0

* fix Python 3.7 builds

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Co-authored-by: James Lamb <jaylamb20@gmail.com>

[ci] [python-package] enforce 'twine check' and 'check-wheel-contents' on Python distributions (#5707)

* [ci] speed up if-else, swig, and lint conda setup

* add 'source activate'

* python constraint

* start removing cuda v1

* comment out CI

* remove more references

* revert some unnecessaary changes

* revert a few more mistakes

* revert another change that ignored params

* sigh

* remove CUDATreeLearner

* fix tests, docs

* fix quoting in setup.py

* restore all CI

* Apply suggestions from code review
Co-authored-by: shiyu1994 <shiyu_k1994@qq.com>

* Apply suggestions from code review

* completely remove cuda_exp, update docs

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Co-authored-by: shiyu1994 <shiyu_k1994@qq.com>

[ci] [python-package] fix missing import, test that lightgbm can be imported with only required dependencies (fixes #5631) (#5632)