Create GitHub repository mapping

curl --request POST \
  --url https://api.xata.tech/organizations/{organizationID}/projects/{projectID}/branches/{branchID}/githubapp/repository \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "githubRepositoryID": 123
}
'

{
  "id": "<string>",
  "githubRepositoryID": 123,
  "project": "<string>",
  "rootBranchId": "<string>",
  "createdAt": "2023-11-07T05:31:56Z",
  "updatedAt": "2023-11-07T05:31:56Z"
}