support negative multiples

[ostrowr]

According to the spec, it's perfectly valid for a negative number to be a multipleOf a positive one:

https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-validation-00#rfc.section.6.2.1

[6.2.1.](https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-validation-00#rfc.section.6.2.1) multipleOf
The value of "multipleOf" MUST be a number, strictly greater than 0.

A numeric instance is valid only if division by this keyword's value results in an integer.

-6 / 1.5 is an integer!

I've also opened an issue in JSON-Schema-Test-Suite to exercise this case:

json-schema-org/JSON-Schema-Test-Suite#888

[Stranger6667]

Awesome! Thanks

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.50%. Comparing base (8acb9de) to head (4ffd458).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1089   +/-   ##
=======================================
  Coverage   94.50%   94.50%           
=======================================
  Files          81       81           
  Lines       22610    22610           
=======================================
  Hits        21367    21367           
  Misses       1243     1243           

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[codspeed-hq]

Merging this PR will not alter performance

✅ 68 untouched benchmarks

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_{Comparing ostrowr:dev/robbie/negative-multipleof (4ffd458) with master (8acb9de)}