Fix hashing for custom `eq` objects (#909)

* Add hashing for eq'd objects

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Add coverage to test

* oops

* Add changelog message

* Revert "Add changelog message"

This reverts commit 0bd3f5cba641046e6b3342093301c755835674d8.

* Address comments

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Hynek Schlawack <hs@ox.cx>
3 files changed