[Schema Inaccuracy] Pull Request Simple Head repo label field may be null

[yanyongyu]

Schema Inaccuracy

The Pull Request Simple object field head.repo may be null if user has deleted the repo, as the Pull Request object.

schemas:
  # incorrect
  pull-request-simple:
    type: object
    title: Pull Request Simple
    properties:
      head:
        type: object
        properties:
          repo:
            "$ref": "#/components/schemas/repository"

  # correct
  pull-request:
    type: object
    title: Pull Request
    properties:
      ...
      head:
        type: object
        properties:
          repo:
            type:
            - object
            - 'null'

Expected

change the repo field to oneof repository / type: null

Reproduction Steps

list pull request using curl -X GET https://api.github.com/repos/apache/pulsar/pulls?state=open

get pull request apache/pulsar#6036 which head repo was deleted

Related to yanyongyu/githubkit#6

[yanyongyu]

The label field can also be null if the branch is deleted according to yanyongyu/githubkit#56