merge cidc-schemas/pulls/581

[crouchcd]

What

• added transcriptome capture v6 to rna enrichment_method (see add transcriptome capture v6 to rna enrichment_method cidc-schemas#581)

Checklist

Please include and complete the following checklist. You can mark an item as complete with the - [x] prefix:

• Tests - Added unit tests for new code, regression tests for bugs and updated the integration tests if required
• Formatting & Linting - black and flake8 have been used to ensure styling guidelines are met
• Type Annotations - All new code has been type annotated in the function signatures using type hints
• Docstrings - Docstrings have been provided for functions
• Documentation - README and CHANGELOG have been updated to explain major changes & new features
• Package version - Manually bumped the API package version in init.py