Bump pyrsistent from 0.14.2 to 0.15.7 in /backend

[dependabot-preview[bot]]

Bumps pyrsistent from 0.14.2 to 0.15.7.

Changelog

Sourced from pyrsistent's changelog.

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

• Fix #179 Fixed 'ignore_extra' factory parameter for pvector. Thanks @ss18 for this!

0.15.4, 2019-07-27

• Fix #174, fix a GC traversal bug in pvector evolver C extension. Thanks @till-varoquaux for finding and fixing this!
• Fix #175, pytest 5 compatibility, this is a quick fix, some more work is needed to get coverage working etc.

0.15.3, 2019-07-07

• Fix #172, catch all exceptions during extension build to reduce chance of corner cases that prevents installation.
• Fix #171, in PVector equality comparison don's assume that other object has a length, check before calling len.
• Fix #168, write warning about failing build of C extension directly to stderr to avoid that pip silences it.
• Fix #155, update PMapEvolver type stub to better reflect implementation.

0.15.2, 2019-05-12

• Fix #166, Propagate 'ignore_extra' param in hierarchy. Thanks @ss18 for this!
• Fix #167, thaw typing. Thanks @nattofriends for this!
• Fix #154, not possible to insert empty pmap as leaf node with transform.

0.15.1, 2019-04-26

• Fix #163 installation broken on Python 2 because of fix of #161, thanks @vphilippon for this! Sorry for the inconvenience.

0.15.0, 2019-04-25

• Python 3.4 is no longer officially supported since it is EOL since 2019-03-18.
• Fix #157, major improvements to type hints. Thanks @je-l for working on this and @nattofriend for reviewing the PR!
• Fix #161, installation fails on some Windows platforms because fallback to Python pvector does not work. Thanks @MaxTaggart for fixing and verifying this!

0.14.11, 2019-02-21

• Fix #152 Don't use __builtin_popcount, this hopefully fixes #147 Error in pvectorc.cp37-win_amd64.pyd file, as well. Thanks @benrg for this!
• Fix #151 Fix compatibility for hypothesis 4. Thanks @felixonmars for this!

0.14.10, 2019-02-09

• Fix #148, only require pytest-runner if running tests. Thanks @ccorbacho for this!

0.14.9, 2019-01-06

• Fix #144, Compile pvectormodule.c on windows. Thanks @ganwell for this!

0.14.8, 2018-12-19

• Fix #142, Improve type stubs. Thanks @arxanas for this!

... (truncated)

Commits

• 4fec827 Prepare version v0.15.7
• f1afb1b Merge pull request #188 from Qhesz/mypy-errors
• db225ad Mypy errors
• 08ba8a1 Merge pull request #187 from ossdev07/arm_support
• 093c615 Adding Travis-Ci Support For Arm64
• ea8a5b9 Merge pull request #185 from michalvi/patch-1
• ef5eaff Set absolute imports for python2 compatibility.
• 33d108f Prepare v0.15.6
• 7c48d83 Fix #182 namespace moduleinit function and make it static
• 8665910 Prepare version v0.15.5
• Additional commits viewable in compare view

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