Update python-dateutil to 2.8.0

[pyup-bot]

This PR updates python-dateutil from 2.7.5 to 2.8.0.

Changelog

2.8.0

==========================

Data updates
------------

- Updated tzdata version to to 2018i.


Features
--------

- Added support for ``EXDATE`` parameters when parsing ``rrule`` strings.
Reported by mlorant (gh issue 410), fixed by nicoe (gh pr 859).
- Added support for sub-minute time zone offsets in Python 3.6+.
Fixed by cssherry (gh issue 582, pr 763)
- Switched the ``tzoffset``, ``tzstr`` and ``gettz`` caches over to using weak
references, so that the cache expires when no other references to the
original ``tzinfo`` objects exist. This cache-expiry behavior is not
guaranteed in the public interface and may change in the future. To improve
performance in the case where transient references to the same time zones
are repeatedly created but no strong reference is continuously held, a
smaller "strong value" cache was also added. Weak value cache implemented by
cs-cordero (gh pr 672, 801), strong cache added by
Gökçen Nurlu (gh issue 691, gh pr 761)


Bugfixes
--------

- Added time zone inference when initializing an ``rrule`` with a specified
``UNTIL`` but without an explicitly specified ``DTSTART``; the time zone
of the generated ``DTSTART`` will now be taken from the ``UNTIL`` rule.
Reported by href (gh issue 652). Fixed by absreim (gh pr 693).
- Fixed an issue where ``parser.parse`` would raise ``Decimal``-specific errors
instead of a standard ``ValueError`` if certain malformed values were parsed
(e.g. ``NaN`` or infinite values). Reported and fixed by
amureki (gh issue 662, gh pr 679).
- Fixed issue in ``parser`` where a ``tzinfos`` call explicitly returning
``None`` would throw a ``ValueError``.
Fixed by parsethis (gh issue 661, gh pr 681)
- Fixed incorrect parsing of certain dates earlier than 100 AD when repesented
in the form "%B.%Y.%d", e.g. "December.0031.30". (gh issue 687, pr 700)
- Add support for ISO 8601 times with comma as the decimal separator in the
``dateutil.parser.isoparse`` function. (gh pr 721)
- Changed handling of ``T24:00`` to be compliant with the standard. ``T24:00``
now represents midnight on the *following* day.
Fixed by cheukting (gh issue 658, gh pr 751)
- Fixed an issue where ``isoparser.parse_isotime`` was unable to handle the
``24:00`` variant representation of midnight. (gh pr 773)
- Added support for more than 6 fractional digits in `isoparse`.
Reported and fixed by jayschwa (gh issue 786, gh pr 787).
- Added 'z' (lower case Z) as valid UTC time zone in isoparser.
Reported by cjgibson (gh issue 820). Fixed by Cheukting (gh pr 822)
- Fixed a bug with base offset changes during DST in ``tzfile``, and refactored
the way base offset changes are detected. Originally reported on
StackOverflow by MartinThoma. (gh issue 812, gh pr 810)
- Fixed error condition in ``tz.gettz`` when a non-ASCII timezone is passed on
Windows in Python 2.7. (gh issue 802, pr 861)
- Improved performance and inspection properties of ``tzname`` methods.
(gh pr 811)
- Removed unnecessary binary_type compatibility shims.
Added by jdufresne (gh pr 817)
- Changed ``python setup.py test`` to print an error to ``stderr`` and exit
with 1 instead of 0. Reported and fixed by hroncok (gh pr 814)
- Added a ``pyproject.toml`` file with build requirements and an explicitly
specified build backend. (gh issue 736, gh prs 746, 863)


Documentation changes
---------------------

- Added documentation for the ``rrule.rrulestr`` function.
Fixed by prdickson (gh issue 623, gh pr 762)
- Added documentation for ``dateutil.tz.gettz``.
Fixed by weatherpattern (gh issue 647, gh pr 704)
- Add documentation for the ``dateutil.tz.win`` module and mocked out certain
Windows-specific modules so that autodoc can still be run on non-Windows
systems. (gh issue 442, pr 715)
- Added changelog to documentation. (gh issue 692, gh pr 707)
- Changed order of keywords in the ``rrule`` docstring.
Reported and fixed by rmahajan14 (gh issue 686, gh pr 695).
- Improved documentation on the use of ``until`` and ``count`` parameters in
``rrule``. Fixed by lucaferocino (gh pr 755).
- Added an example of how to use a custom ``parserinfo`` subclass to parse
non-standard datetime formats in the examples documentation for ``parser``.
Added by prdickson (gh 753)
- Added doctest examples to ``tzfile`` documentation.
Patch by weatherpattern (gh pr 671)
- Updated the documentation for ``relativedelta``'s ``weekday`` arguments.
Fixed by kvn219 huangy22 and ElliotJH (gh pr 673)
- Improved explanation of the order that ``relativedelta`` components are
applied in. Fixed by kvn219 huangy22 and ElliotJH (gh pr 673)
- Expanded the description and examples in the ``relativedelta`` class.
Contributed by andrewcbennett (gh pr 759)
- Improved the contributing documentation to clarify where to put new changelog
files. Contributed by andrewcbennett (gh pr 757)
- Fixed a broken doctest in the ``relativedelta`` module.
Fixed by nherriot (gh pr 758).
- Changed the default theme to ``sphinx_rtd_theme``, and changed the sphinx
configuration accordingly. (gh pr 707)
- Reorganized ``dateutil.tz`` documentation and fixed issue with the
``dateutil.tz`` docstring. (gh pr 714)
- Cleaned up malformed RST in the ``tz`` documentation.
(gh issue 702, gh pr 706)
- Corrected link syntax and updated URL to https for ISO year week number
notation in ``relativedelta`` examples. (gh issue 670, pr 711)


Misc
----

- GH 674, GH 688, GH 699, GH 720, GH 723, GH 726, GH 727, GH 740,
GH 750, GH 760, GH 767, GH 772, GH 773, GH 780, GH 784, GH 785,
GH 791, GH 799, GH 813, GH 836, GH 839, GH 857

Links

• PyPI: https://pypi.org/project/python-dateutil
• Changelog: https://pyup.io/changelogs/python-dateutil/
• Docs: https://dateutil.readthedocs.io

[coveralls]

Pull Request Test Coverage Report for Build 654

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 44.861%

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Totals
Change from base Build 639:	0.0%
Covered Lines:	323
Relevant Lines:	720

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