Bump sortedcontainers from 1.5.9 to 2.1.0

[dependabot-preview]

Bumps sortedcontainers from 1.5.9 to 2.1.0.

Changelog

Sourced from sortedcontainers's changelog.

2.1.0 (2018-11-21)

Miscellaneous

• Small updates to docs and tests for Python 3.7.

2.0.5 (2018-09-03)

Bugfixes

• Change imports for Abstract Base Classes to collections.abc to avoid
  warnings in Python 3.7.

2.0.4 (2018-06-06)

Bugfixes

• SortedDict methods iterkeys, iteritems, itervalues, viewkeys,
  viewitems, and viewvalues are not implemented for Python 2. Attribute
  lookup now raises :exc:AttributeError.

2.0.3 (2018-05-31)

API Changes

• Accessing SortedDict.iloc will emit DeprecationWarning.

Bugfixes

• SortedSet.__rsub__ erroneously reversed its arguments. The method has been
  removed in favor of the inherited Set.__rsub__ which has a correct
  implementation.
• :class:SortedKeysView and :class:SortedValuesView set-operations now
  return :class:SortedSet objects to better match the semantics of version 1.

Miscellaneous

• The source distribution no longer contains the docs and tests
  directories. If you need these, then please download an archive from
  Github. Version control is tagged with the version released to PyPI.

2.0.2 (2018-05-21)

API Changes

... (truncated)

Commits

• e05634b Bump version to 2.1.0
• 5ca6235 Changes for Python 3.7
• c8f1e1d Merge pull request #104 from asottile/patch-1
• d85e8b1 performance.rst: fix typo
• 64dfae3 Bump version to 2.0.5
• f362cba Add blurb for 2.0.5
• 428beb8 Couple fixes for tox/lint
• 41eb03f Update collections.abc imports to avoid Python 3.7 warnings
• 022167c Bump version to 2.0.4
• 3367ea5 Make iteritems, iterkeys, itervalues, viewitems, viewkeys, viewvalues raise A...
• Additional commits viewable in compare view

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