Update black to 20.8b1

[pyup-bot]

This PR updates black from 19.3b0 to 20.8b1.

Changelog

20.8b1

_Packaging_

- explicitly depend on Click 7.1.2 or newer as `Black` no longer works with versions
older than 7.0

20.8b0

_Black_

- re-implemented support for explicit trailing commas: now it works consistently within
any bracket pair, including nested structures (1288 and duplicates)

- `Black` now reindents docstrings when reindenting code around it (1053)

- `Black` now shows colored diffs (1266)

- `Black` is now packaged using 'py3' tagged wheels (1388)

- `Black` now supports Python 3.8 code, e.g. star expressions in return statements
(1121)

- `Black` no longer normalizes capital R-string prefixes as those have a
community-accepted meaning (1244)

- `Black` now uses exit code 2 when specified configuration file doesn't exit (1361)

- `Black` now works on AWS Lambda (1141)

- added `--force-exclude` argument (1032)

- removed deprecated `--py36` option (1236)

- fixed `--diff` output when EOF is encountered (526)

- fixed ` fmt: off` handling around decorators (560)

- fixed unstable formatting with some ` type: ignore` comments (1113)

- fixed invalid removal on organizing brackets followed by indexing (1575)

- introduced `black-primer`, a CI tool that allows us to run regression tests against
existing open source users of Black (1402)

- introduced property-based fuzzing to our test suite based on Hypothesis and
Hypothersmith (1566)

- implemented experimental and disabled by default long string rewrapping (1132),
hidden under a `--experimental-string-processing` flag while it's being worked on;
this is an undocumented and unsupported feature, you lose Internet points for
depending on it (1609)

Vim plugin

- prefer virtualenv packages over global packages (1383)

19.10b0

- added support for PEP 572 assignment expressions (711)

- added support for PEP 570 positional-only arguments (943)

- added support for async generators (593)

- added support for pre-splitting collections by putting an explicit trailing comma
inside (826)

- added `black -c` as a way to format code passed from the command line (761)

- --safe now works with Python 2 code (840)

- fixed grammar selection for Python 2-specific code (765)

- fixed feature detection for trailing commas in function definitions and call sites
(763)

- ` fmt: off`/` fmt: on` comment pairs placed multiple times within the same block of
code now behave correctly (1005)

- _Black_ no longer crashes on Windows machines with more than 61 cores (838)

- _Black_ no longer crashes on standalone comments prepended with a backslash (767)

- _Black_ no longer crashes on `from` ... `import` blocks with comments (829)

- _Black_ no longer crashes on Python 3.7 on some platform configurations (494)

- _Black_ no longer fails on comments in from-imports (671)

- _Black_ no longer fails when the file starts with a backslash (922)

- _Black_ no longer merges regular comments with type comments (1027)

- _Black_ no longer splits long lines that contain type comments (997)

- removed unnecessary parentheses around `yield` expressions (834)

- added parentheses around long tuples in unpacking assignments (832)

- added parentheses around complex powers when they are prefixed by a unary operator
(646)

- fixed bug that led _Black_ format some code with a line length target of 1 (762)

- _Black_ no longer introduces quotes in f-string subexpressions on string boundaries
(863)

- if _Black_ puts parenthesis around a single expression, it moves comments to the
wrapped expression instead of after the brackets (872)

- `blackd` now returns the version of _Black_ in the response headers (1013)

- `blackd` can now output the diff of formats on source code when the `X-Diff` header is
provided (969)

Links

• PyPI: https://pypi.org/project/black
• Changelog: https://pyup.io/changelogs/black/
• Repo: https://github.com/psf/black

[pyup-bot]

Closing this in favor of #231