Deprecate HashableDict in favor of frozendict

[kenodegard]

Description

Instead of using a customized HashableDict implementation we can just use the frozendict library (which conda already depends on). Using frozendict also means we can avoid calling deepcopy (frozendict takes care of this for us).

Checklist - did you ...

• Add a file to the news directory (using the template) for the next release's release notes?
• Add / update necessary tests?
• Add / update outdated documentation?

[codspeed-hq]

CodSpeed Performance Report

Merging #5284 will not alter performance

_{Comparing kenodegard:deprecate-hashabledict (ea171c0) with main (b7ea405)}

Summary

✅ 3 untouched benchmarks

[kenodegard]

The current version of frozendict.deepfreeze mutates the original object. This is undesired behavior and needs to be corrected. Hopefully it can be addressed upstream, see Marco-Sulla/python-frozendict#96 & Marco-Sulla/python-frozendict#97.

Resolved upstream, frozendict 2.4.2 has been released.