fix review bot: updated to v2.4.1 with fix (#282)

This contains the fix for paritytech/review-bot#118, which is a breaking
change introduced in V1.2.0 which causes the `Identity` object to become
a tuple.

The updated code gets the first element of the tuple.

---

Replaced the action `tibdex/github-app-token` for
`actions/create-github-app-token` which works the same way but is
developed by GitHub (which should make it more secure)

- [x] Does not require a CHANGELOG entry

.github/workflows/review-bot.yml

@@ -21,12 +21,12 @@ jobs:
           artifact-name: pr_number
       - name: Generate token
         id: team_token
-        uses: tibdex/github-app-token@v1
+        uses: actions/create-github-app-token@v1.9.3
         with:
-          app_id: ${{ secrets.REVIEW_APP_ID }}
-          private_key: ${{ secrets.REVIEW_APP_KEY }}
+          app-id: ${{ secrets.REVIEW_APP_ID }}
+          private-key: ${{ secrets.REVIEW_APP_KEY }}
       - name: "Evaluates PR reviews and assigns reviewers"
-        uses: paritytech/review-bot@v2.4.0
+        uses: paritytech/review-bot@v2.4.1
         with:
           repo-token: ${{ secrets.GITHUB_TOKEN }}
           team-token: ${{ steps.team_token.outputs.token }}