fix: includes additional properties in schema

[foray1010]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
  • (seems nothing needed to be updated)

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Other... Please describe:

What is the current behavior?

additionalProperties in ApiProperty is not moved to schema in swagger.json, which is invalid

What is the new behavior?

shouldm move additionalProperties to schema

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[foray1010]

@kamilmysliwiec would be great if we can have a new release with this fix :)