Release v2.2.0

Changes in this Release

What's Changed

• Update versions in requirements.txt by @aaronspring in #673
• add valid_time as initialized coord by @aaronspring in #675
• Bump actions/github-script from 4.1 to 5 by @dependabot in #676
• add tests to show #586 can be closed by @aaronspring in #677
• Fixes after #675 by @aaronspring in #678
• Update print_versions.py by @aaronspring in #681
• Update bias_removal.py by @aaronspring in #682
• setup_requires into pyproject.toml by @aaronspring in #684
• optional dependencies by @aaronspring in #686
• implement LESS by @aaronspring in #687
• Verify_groupby by @aaronspring in #690
• Remove seasonality by @aaronspring in #688
• typing annotations by @aaronspring in #692
• Refactor add_attrs into classes verify() by @aaronspring in #694
• add attrs to new coords by @aaronspring in #697
• fix valid_time freq bug by @aaronspring in #700
• add HindcastEnsemble.plot_alignment() by @aaronspring in #702
• reduce skipped tests by @aaronspring in #704
• Fix climatology season and weekofyear by @aaronspring in #703
• ♻️ resample uninitialized from initialized in HindcastEnsemble by @aaronspring in #691
• 🧷persistence with initialized lead=0 by @aaronspring in #706
• improve docs by @aaronspring in #708
• 📚 revise docs incl. notebooks by @aaronspring in #709
• use sphinxcontrib-bibtex by @aaronspring in #710
• release v2.2.0 by @aaronspring in #711

Full Changelog: v2.1.6...v2.2.0