moved to `observed=True` in pandas grouping to filter out missing data

version bump

bumped up version

updated version number and license header

improved all posthocs and omnibus tests for block design data (fixes #76

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reimplemented multiple tests, improved type hints, linted and formatt…

…ed code with ruff

Update __init__.py

Update posthocs_api.rst

fixed conover post hoc test for unreplicated blocked data

badges updated