Anchorpoint

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- bugfix: TextPositionSet init wouldn't accept serialized position selector
- pass selection to TextPositionSet init in list

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- fix error in specifying Pydantic version in setup.py

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- add tests for Python 3.12
- update models to pydantic v2
- add None checks for type checker
- fix type issue with TextPositionSet.sub()
- add type hints to TextPositionSet.from_quotes()
- replace CircleCI with GitHub CI
- remove unreachable validation check

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- passing TextPositionSet to from_selection_sequence doesn't cause error
- fix bug: Range with end "Inf" caused string slicing error
- add TextPositionSet.from_quotes
- remove TextSelector class
- start_less_than_end is no longer a root_validator

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- python-ranges by Superbird11 is imported instead of vendored

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- TextPositionSelector no longer inherits from Range
- TextPositionSet no longer inherits from RangeSet
- TextPositionSelector no longer has real_start and real_end that can differ from start and end
- Selectors and TextPositionSets are Pydantic models
- TextSelector is Pydantic model for either Quote or Position Selector
- remove Marshmallow schemas
- update type annotations for TextPositionSelector.from_range
- add TestQuoteSelector.as_unique_position method
- TextPositionSet can include TextQuoteSelectors
- add convert_quotes_to_positions method to TextPositionSet
- replace `TextPositionSet.selectors` field with `positions` and `quotes`
- change `as_quote_selector` method to `as_quote`
- TextPositionSet.add_margin includes quotes
- fix bug: subtracting int from selector set caused quotes to be lost
- add __ge__ and __gt__ methods for TextPositionSelector
- add Selecting Text with Anchorpoint guide