Issue assignee has no properties

[owlas]

In the issues schema, there is an assignee field of type object but it has no properties. This causes an error with bigquery taps because the schema for json has to be defined (in postgres, it just accepts a json blob).

Is this intentional or incomplete? I'm happy to open a PR. Is there a way to reuse assignee.json ?

tap-github/tap_github/schemas/issues.json

Lines 75 to 80 in 778682b

	"assignee": {
	"type": [
	"null",
	"object"
	],
	"properties": {}