- update to 0.12.1
- use python3-Sphinx for build

- update for singlespec
- update to 0.12.1
* deprecate werkzeug.script
* Use `inspect.getfullargspec` internally when available as
`inspect.getargspec` is gone in 3.6
* Added support for status code 451 and 423
* Improved the build error suggestions. In particular only if
someone stringifies the error will the suggestions be calculated.
* Added support for uWSGI's caching backend.
* Fix a bug where iterating over a `FileStorage` would result in an infinite
loop.
* Datastructures now inherit from the relevant baseclasses from the
`collections` module in the stdlib. See #794.
* Add support for recognizing NetBSD, OpenBSD, FreeBSD, DragonFlyBSD platforms
in the user agent string.
* Recognize SeaMonkey browser name and version correctly
* Recognize Baiduspider, and bingbot user agents
* If `LocalProxy`'s wrapped object is a function, refer to it with __wrapped__
attribute.
* The defaults of ``generate_password_hash`` have been changed to more secure
ones, see pull request ``#753``.
* Add support for encoding in options header parsing, see pull request
``#933``.
* ``test.Client`` now properly handles Location headers with relative URLs, see
pull request ``#879``.
* When `HTTPException` is raised, it now prints the description, for easier
debugging.