src/poky:python3-pyyaml: upgrade 5.4.1 -> 6.0

Now uses "vendored" distutils from setuptools by default
rather than from Python stdlib.

Changes
=======

* yaml/pyyaml#327
  -- Change README format to Markdown
* yaml/pyyaml#483
  -- Add a test for YAML 1.1 types
* yaml/pyyaml#497
  -- fix float resolver to ignore `.` and `._`
* yaml/pyyaml#550
  -- drop Python 2.7
* yaml/pyyaml#553
  -- Fix spelling of “hexadecimal”
* yaml/pyyaml#556
  -- fix representation of Enum subclasses
* yaml/pyyaml#557
  -- fix libyaml extension compiler warnings
* yaml/pyyaml#560
  -- fix ResourceWarning on leaked file descriptors
* yaml/pyyaml#561
  -- always require `Loader` arg to `yaml.load()`
* yaml/pyyaml#564
  -- remove remaining direct distutils usage

(From OE-Core rev: 2abc7a612a71b3594f3183fbb824a708269ae694)

Signed-off-by: Tim Orling <timothy.t.orling@intel.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>