Fix bytes rendered wrong

[ischaojie]

fixes: #31

I'm not quite sure what the reason is for the format being specified as binary in JsonSchemaFile, but comparing the implementation in react-jsonschema-form here format=data-url, a detail not specified in the json-schema standard, and it looks like we could use a similar implementation here?

[samuelcolvin]

I don't think this fixes it, but I might be wrong. We need to fix tests and check all cases are covered.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (6b7c7cb) 83.66% compared to head (7ec0913) 83.81%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #106      +/-   ##
==========================================
+ Coverage   83.66%   83.81%   +0.15%     
==========================================
  Files          10       10              
  Lines         661      661              
==========================================
+ Hits          553      554       +1     
+ Misses        108      107       -1     

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[ischaojie]

ref: https://rjsf-team.github.io/react-jsonschema-form/docs/usage/widgets/#file-widgets