Update sanic to 19.6.3

[pyup-bot]

This PR updates sanic from 19.3.1 to 19.6.3.

Changelog

19.6.3

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

Features
********

- Enable Towncrier Support

As part of this feature, `towncrier` is being introduced as a mechanism to partially  automate the process
of generating and managing change logs as part of each of pull requests. (`1631 <https://github.com/huge-success/sanic/issues/1631>`__)


Improved Documentation
**********************

- Documentation infrastructure changes

- Enable having a single common `CHANGELOG` file for both GitHub page and documentation
- Fix Sphinix deprecation warnings
- Fix documentation warnings due to invalid `rst` indentation
- Enable common contribution guidelines file across GitHub and documentation via `CONTRIBUTING.rst` (`1631 <https://github.com/huge-success/sanic/issues/1631>`__)

19.6.2

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

Features
********

* 
 `1562 <https://github.com/huge-success/sanic/pull/1562>`_
 Remove ``aiohttp`` dependencey and create new ``SanicTestClient`` based upon
 `requests-async <https://github.com/encode/requests-async>`_

* 
 `1475 <https://github.com/huge-success/sanic/pull/1475>`_
 Added ASGI support (Beta)

* 
 `1436 <https://github.com/huge-success/sanic/pull/1436>`_
 Add Configure support from object string


Bugfixes
********

* 
 `1587 <https://github.com/huge-success/sanic/pull/1587>`_
 Add missing handle for Expect header.

* 
 `1560 <https://github.com/huge-success/sanic/pull/1560>`_
 Allow to disable Transfer-Encoding: chunked.

* 
 `1558 <https://github.com/huge-success/sanic/pull/1558>`_
 Fix graceful shutdown.

* 
 `1594 <https://github.com/huge-success/sanic/pull/1594>`_
 Strict Slashes behavior fix

Deprecations and Removals
*************************

*
 `1544 <https://github.com/huge-success/sanic/pull/1544>`_
 Drop dependency on distutil

* 
 `1562 <https://github.com/huge-success/sanic/pull/1562>`_
 Drop support for Python 3.5

* 
 `1568 <https://github.com/huge-success/sanic/pull/1568>`_
 Deprecate route removal.

.. warning::
 Sanic will not support Python 3.5 from version 19.6 and forward. However,
 version 18.12LTS will have its support period extended thru December 2020, and
 therefore passing Python's official support version 3.5, which is set to expire
 in September 2020.

Links

• PyPI: https://pypi.org/project/sanic
• Changelog: https://pyup.io/changelogs/sanic/
• Repo: http://github.com/huge-success/sanic/

[coveralls]

Pull Request Test Coverage Report for Build 1818

• 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 98.573%

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Totals
Change from base Build 1815:	0.0%
Covered Lines:	4215
Relevant Lines:	4276

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💛 - Coveralls