Remove usages of #hash to avoid potential hash collisions

[jemmaissroff]

This PR removes usage of #hash because there is a potential for hash collisions leading to incorrect memoized results in our current implementation.

See this issue for further explanation.

Still todo on this PR:

• Once benchmarks run, add content around what we do differently than dry-rb
• Copy the table printed at the end of the latest benchmark results into the README.md and update this PR
• If this change merits an update to CHANGELOG.md, add an entry following Keep a Changelog guidelines with semantic versioning

[codecov]

Codecov Report

Merging #216 (19155f5) into main (645f5a6) will not change coverage.
The diff coverage is 100.00%.

❗ Current head 19155f5 differs from pull request most recent head de974ba. Consider uploading reports for the commit de974ba to get more accurate results

@@            Coverage Diff            @@
##              main      #216   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            2         2           
  Lines          213       213           
=========================================
  Hits           213       213           

Impacted Files	Coverage Δ
lib/memo_wise.rb	100.00% <100.00%> (ø)
lib/memo_wise/internal_api.rb	100.00% <100.00%> (ø)

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[JacobEvelyn]

We no longer need @_memo_wise_hashes, right?

[jemmaissroff]

Resolved in #219