Update method to determine latest valid PR reviews

[LoveIsGrief]

After lastPushedAt was deprecated, one still needs a method to determine which reviews are still valid. After a review has been made, the branch can still be pushed to.

One way to do this is to check if the commit associated with the review is also the latest.

query($repoName: String!, $repoOwner: String!, $prNumber: Int!){
          repository(name: $repoName, owner: $repoOwner) {
            pullRequest(number: $prNumber) {
              title
                number
      		  commits(first: 1){
                  nodes{
                    id
                  }
                }
                latestReviews(last: 100) {
                  nodes {
                    state
                    commit {
                      id
                    }
                    author {
                      login
                    }
                    publishedAt
                  }
                }
            }
          }
        }

One can use the latestReviews[].commit.id == pullRequest.commits[-1].id.

Example:

• Graph Explorer https://docs.github.com/en/graphql/overview/explorer
• PR nixos/unifi: add test and additional config options [WIP] NixOS/nixpkgs#68884

Call with

{
  "repoName": "nixpkgs",
  "repoOwner": "NixOS",
  "prNumber": 68884
}

Output

{
  "data": {
    "repository": {
      "pullRequest": {
        "title": "nixos/unifi: add test and additional config options [WIP]",
        "number": 68884,
        "commits": {
          "nodes": [
            {
              "id": "MDE3OlB1bGxSZXF1ZXN0Q29tbWl0MzE3NzczMzkyOjcxMDgwZGZlYjRhNDM1MzNlMTYwYjdhYjkyNzkxZmRjNGVmMTU1Mzk="
            }
          ]
        },
        "latestReviews": {
          "nodes": [
            {
              "state": "COMMENTED",
              "commit": null,
              "author": {
                "login": "aanderse"
              },
              "publishedAt": "2019-09-17T01:06:03Z"
            },
            {
              "state": "CHANGES_REQUESTED",
              "commit": {
                "id": "MDY6Q29tbWl0NDU0MjcxNjo3MTA4MGRmZWI0YTQzNTMzZTE2MGI3YWI5Mjc5MWZkYzRlZjE1NTM5"
              },
              "author": {
                "login": "veehaitch"
              },
              "publishedAt": "2021-05-20T09:33:23Z"
            }
          ]
        }
      }
    }
  }
}

Maybe the comparison can just be review.state == "APPROVED" && review.commit.id != null.