Bug fixes for custom dictionaries

[chrisbrickhouse]

• Introduces tests for cmudictionary.py which resolves #59 and uncovered a previously unknown bug (now fixed; described in 6578a09ae0ec4fbdc02da400f72a3749d4c9ed9f commit message).
• Absent plans for new features, the next release will likely be bug fixes so bump the version number to 2.0.2-dev while we collect fixes.
• Upgrade dependencies in poetry.lock
• Expand authorship info in pyproject.toml partly to prep for future debian packaging
• Improve documentation for end users in 6578a09ae0ec4fbdc02da400f72a3749d4c9ed9f

[chrisbrickhouse]

Apologies for the force-push, only way to make the history sane on my main branch. Updated the description to account for hash changes and include the doc update