Schema description update should be considered as a metadata change

复现提供的 OpenAPI diff，然后检查所引用的第 160 行附近的 core/src/main/java/org/openapitools/openapidiff/core/model/ChangedSchema.java，同时检查 ChangedMetadata.java 以及 ChangedSchema.java 中的元数据处理。完成的标准是：仅涉及 schema 描述的变更会被报告为元数据变更，而不是仅被报告为向后兼容。

Hello,

When diffing this spec:

openapi: 3.0.3
info:
  title: Test
paths:
  /foo:
    post:
      requestBody:
        content:
          application/json:
            schema:
              type: string
              description: desc v1

with this one:

openapi: 3.0.3
info:
  title: Test
paths:
  /foo:
    post:
      requestBody:
        content:
          application/json:
            schema:
              type: string
              description: desc v2

I get the following output:

==========================================================================
==                            API CHANGE LOG                            ==
==========================================================================
                                   Test                                   
--------------------------------------------------------------------------
--                            What's Changed                            --
--------------------------------------------------------------------------
- POST   /foo
  Request:
        - Changed application/json
          Schema: Backward compatible
--------------------------------------------------------------------------
--                                Result                                --
--------------------------------------------------------------------------
                   API changes are backward compatible                    
--------------------------------------------------------------------------

Since only the description field changed, I would expect a "metadata" change instead of a "compatible" one.

Changes to the description are correctly marked as metadata ones internally (see here and here) but I suspect the final value that is picked up to be the default one returned here. I don't have the time or means to debug it further however.

Tested version: 2.1.0-beta.11