py-semantic_version: updated to 2.8.2

2.8.2
*Bugfix:*
    * Restore computation of ``Spec.specs`` for single-term expressions
      (``>=0.1.2``)

2.8.1
*Bugfix:*
    * Restored attribute ``Spec.specs``, removed by mistake during the refactor.

2.8.0
*New:*
    * Restore support for Python 2.

2.7.1
*Bugfix:*
    * Fix parsing of npm-based caret expressions.

2.7.0
This release brings a couple of significant changes:
- Allow to define several range description syntaxes (``SimpleSpec``, ``NpmSpec``, ...)
- Fix bugs and unexpected behaviours in the ``SimpleSpec`` implementation.

Backwards compatibility has been kept, but users should adjust their code for the new features:
- Use ``SimpleSpec`` instead of ``Spec``
- Replace calls to ``Version('1.2', partial=True)`` with ``SimpleSpec('~1.2')``
- ``iter(some_spec)`` is deprecated.

*New:*
    * Allow creation of a ``Version`` directly from parsed components, as keyword arguments
      (``Version(major=1, minor=2, patch=3)``)
    * Add ``Version.truncate()`` to build a truncated copy of a ``Version``
    * Add ``NpmSpec(...)``, following strict NPM matching rules (https://docs.npmjs.com/misc/semver)
    * Add ``Spec.parse('xxx', syntax='<syntax>')`` for simpler multi-syntax support
    * Add ``Version().precedence_key``, for use in ``sort(versions, key=lambda v: v.precedence_key)`` calls.
      The contents of this attribute is an implementation detail.

*Bugfix:*
    * Fix inconsistent behaviour regarding versions with a prerelease specification.

*Deprecated:*
    * Deprecate the ``Spec`` class (Removed in 3.1); use the ``SimpleSpec`` class instead
    * Deprecate the internal ``SpecItem`` class (Removed in 3.0).
    * Deprecate the ``partial=True`` form of ``Version``; use ``SimpleSpec`` instead.

*Removed:*
    * Remove support for Python2 (End of life 4 months after this release)

*Refactor:*
    * Switch spec computation to a two-step process: convert the spec to a combination
      of simple comparisons with clear semantics, then use those.


(adam)