fix: dependency graph handles oneOf allOf nesting

[mnahkies]

the latest github api definitions (#72) include structures like:

    repository-rule-detailed:
      title: Repository Rule
      type: object
      description: A repository rule with ruleset details.
      oneOf:
      - allOf:
        - "$ref": "#/components/schemas/repository-rule-creation"
        - "$ref": "#/components/schemas/repository-rule-ruleset-info"
      - allOf:
        - "$ref": "#/components/schemas/repository-rule-update"
        - "$ref": "#/components/schemas/repository-rule-ruleset-info"

which weren't being considered by the dependency graph correctly, causing use before define errors to be emitted.