Update pyrsistent requirement from <0.17.0 to <0.19.0

[dependabot]

Updates the requirements on pyrsistent to permit the latest version.

Changelog

Sourced from pyrsistent's changelog.

0.18.0, 2021-06-28

• Fix #209 Update freeze recurse into pyrsistent data structures and thaw to recurse into lists and dicts, Thanks @​phil-arh for this! NB! This is a backwards incompatible change! To keep the old behaviour pass strict=False to freeze and thaw.
• Fix #226, stop using deprecated exception.message. Thanks @​hexagonrecursion for this!
• Fix #211, add union operator to persistent maps. Thanks @​bowbahdoe for this!
• Fix #194, declare build dependencies through pyproject.toml. Thanks @​jaraco for this!
• Officially drop Python 3.5 support.
• Fix #223, release wheels for all major platforms. Thanks @​johnthagen for helping out with this!
• Fix #221, KeyError obscured by TypeError if key is a tuple. Thanks @​ganwell for this!
• Fix LICENSE file name spelling. Thanks @​ndowens and @​barentsen for this!
• Fix #216, add abstractmethod decorator for CheckedType and ABCMeta for _CheckedTypeMeta. Thanks @​ss18 for this!
• Fix #228, rename example classes in tests to avoid name clashes with pytest.

0.17.3, 2020-09-13

• Fix #208, release v0.17.3 with proper meta data requiring Python >= 3.5.

0.16.1, 2020-09-13

• Add "python_requires >= 2.7" to setup.py in preparation for Python 2.7 incompatible updates in 0.17. This is the last version of pyrsistent that can be used with Python 2.7.

0.17.2 (yanked awaiting proper fix for Python 3 req), 2020-09-09

• Same as 0.17.1 released with more recent version of setuptools to get proper meta data for in place.

0.17.1 (yanked for proper meta data), 2020-09-09

• Restrict package to Python >= 3.5 to not break unpinned Python 2 dependencies. Thanks @​vphilippon for this!

0.17.0 (yanked for Python 2 compatibility), 2020-09-08

• Remove Python 2 support code. This includes dropping some compatibility code and the dependency on six. Thanks @​djailla for this.
• Fix #200, python 3 exception chaining. This is a minor backwards incompatibility, hence stepping to 0.17.0. Thanks @​cool-RR for this!

0.16.0, 2020-03-24

• No major updates but Python 2 support no longer guaranteed.
• Fix #192, 'ignore_extra' for 'pvector_field'. Thanks @​ss18 for this!
• Fix #191, include LICENCE in distribution. Thanks @​johnthagen for this!
• Fix #190, minor MyPy errors. Thanks @​Qhesz for this!

0.15.7, 2020-01-07

• NOTE! This is the last version of Pyrsistent that officially supports Python 2.X!
• Fix #186, type errors with more recent versions of MyPy. Thanks @​qhesz for this!
• Build and test on ARM during CI. Thanks @​ossdev07 for this!
• Set absolute imports for python2 compatibility. Thanks @​michalvi for this!

0.15.6, 2019-11-23

• Fix #182 moduleinit name clash.

0.15.5, 2019-10-27

... (truncated)

Commits

• 1b8e85e Prepare version v0.18.0
• e3df30b Fix #228 rename classes for test objects to not clash with pytest naming conv...
• 7742091 Fix broken badge link in README
• c435043 Changelog placeholder for 0.17.4
• 5b2530f Replace Travis CI with basic Github actions for testing
• fd062ea Add jobs for creating source dist and pypi publishing
• aa6efa5 Add basic GH actions flow for tests
• 0266da8 Add GH actions linter
• 19e426f Merge pull request #227 from naveen521kk/wheels
• adb438f Change the return type of PVector_hash
• Additional commits viewable in compare view

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[dependabot]

Superseded by #19.