v0.8.2

Released on October 8th, 2019.

• Fix deprecated convert attribute in constraint_modifiers.py to
  comply with attrs package release 19.2.0 (see also
  https://www.attrs.org/en/stable/changelog.html_). (#270)
• Fix typo in InvalidConstraint error message. (#266)
• Fix error with UndeterminedClausePolicy not suggesting best packages. (#268)

Internals

• Change minimum supported version of attrs to 17.4.0. (#270)