intake/intake-esm: intake-esm v2021.8.17

(full changelog) Enhancements made Add pydantic models to facilitate data validation #347 (@andersy005) Maintenance and upkeep improvements [pre-commit.ci] pre-commit autoupdate #355 (@pre-commit-ci) skip cmip6_preprocessing tests for the time being #354 (@andersy005) Bump styfle/cancel-workflow-action from 0.9.0 to 0.9.1 #348 (@dependabot) Update pre-commit hooks #346 (@andersy005) Bump codecov/codecov-action from 1 to 2.0.2 #345 (@dependabot) Disable workflows on Forks #342 (@andersy005) Add missing test dependency #340 (@andersy005) Code refactoring #338 (@andersy005) Bump pre-commit/action from v2.0.2 to v2.0.3 #337 (@dependabot) Bump styfle/cancel-workflow-action from 0.8.0 to 0.9.0 #334 (@dependabot) Bump pre-commit/action from v2.0.0 to v2.0.2 #333 (@dependabot) Bump styfle/cancel-workflow-action from 0.7.0 to 0.8.0 #322 (@dependabot) Fix CI #321 (@andersy005) Fix Tests: Use a publicly available s3 object #318 (@andersy005) Bump styfle/cancel-workflow-action from 0.6.0 to 0.7.0 #316 (@dependabot) Documentation improvements Add cesm2-le catalog #349 (@mgrover1) Docs: Execute all notebooks #341 (@andersy005) Enable comments in docs via sphinx-comments #326 (@andersy005) Other merged PRs pin pandas version #356 (@mgrover1) Contributors to this release (GitHub contributors page for this release) @andersy005 | @dependabot | @mgrover1 | @pre-commit-c