Fix Typo in IOpenApiReadOnlyExtensible.cs

[say25]

Pull Request

Description

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Other (please describe):

Related Issue(s)

Changes Made

Testing

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed
• All existing tests pass

Checklist

• My code follows the code style of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Versions applicability

• My change applies to the version 1.X of the library, if so PR link:
• My change applies to the version 2.X of the library, if so PR link:
• My change applies to the version 3.X of the library, if so PR link:
• I have evaluated the applicability of my change against the other versions above.

See the contributing guidelines for more information about how patches are applied across multiple versions.

Additional Notes

[baywet]

Thank you for the contribution!
Would you mind please doing the same on the support/v2 branch please?