Support to disallow duplicate map key at parsing

[goccy]

fix #226

Breaking Changes

Previously, using the same map key did not result in a parsing error, but from now on, it will throw an error by default. If you want to keep the previous behavior, specify the parser.AllowDuplicateMapKey() option. Similarly, during Decode, it will also throw an error by default. To keep the previous behavior, specify the yaml.AllowDuplicateMapKey() option when decoding.

Also, I deprecated yaml.DisallowDuplicateKey option. That is not necessary.

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.16%. Comparing base (4385176) to head (1cf609f).

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #531      +/-   ##
==========================================
- Coverage   79.23%   79.16%   -0.07%     
==========================================
  Files          17       18       +1     
  Lines        6216     6245      +29     
==========================================
+ Hits         4925     4944      +19     
- Misses        977      985       +8     
- Partials      314      316       +2     

[alexandear]

Also, I deprecated yaml.DisallowDuplicateKey option. That is not necessary.

Hi, it looks like the yaml.DisallowDuplicateKey option was removed instead of being deprecated. According to Semantic Versioning, this constitutes an incompatible API change, which requires a major version increment.

In the future, please consider deprecating options with the comment first before removing them to maintain backward compatibility. For example, you can add the comment // Deprecated: use ... instead, and the IDE will highlight this function as deprecated.

Thank you!