fix: Return "Unknown specification" error on https-prefixed $schema for Draft 4, 5, 6

[Stranger6667]

Resolves #629

[codecov]

Codecov Report

Attention: Patch coverage is 94.44444% with 1 line in your changes missing coverage. Please review.

Project coverage is 87.90%. Comparing base (832d7d1) to head (e677437).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
crates/jsonschema/src/options.rs	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #631      +/-   ##
==========================================
+ Coverage   87.88%   87.90%   +0.01%     
==========================================
  Files          92       92              
  Lines       13307    13318      +11     
==========================================
+ Hits        11695    11707      +12     
+ Misses       1612     1611       -1     

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[codspeed-hq]

CodSpeed Performance Report

Merging #631 will not alter performance

_{Comparing dd/fix-schema-https (e677437) with master (832d7d1)}

Summary

✅ 45 untouched benchmarks