get commit id from tagname

params.json

{
  "owner": "Quramy",
  "repository": "tsuquyomi",
  "tag": "v0.8.0"
}

query.gql

query MyQuery($tag: String!, $owner: String!, $repository: String!) {
  repository(owner: $owner, name: $repository) {
    nameWithOwner
    ref(qualifiedName: $tag) {
      name
      target {
        oid
      }
    }
  }
}

sample result:

{
  "data": {
    "repository": {
      "nameWithOwner": "Quramy/tsuquyomi",
      "ref": {
        "name": "v0.8.0",
        "target": {
          "oid": "254f890f2f216a5179d8612f8a2b6fa15ca461ab"
        }
      }
    }
  }
}