Use pullbot token instead of GITHUB_TOKEN on the Danger Action (#33900)

Summary:
GITHUB_TOKEN doesn't have write permissions on forks, using the pullbot token instead.

https://docs.github.com/en/actions/security-guides/automatic-token-authentication#permissions-for-the-github_token

## Changelog

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[Internal] - Use pullbot token instead of GITHUB_TOKEN on the Danger Action

Pull Request resolved: #33900

Test Plan: CI will validate it

Reviewed By: cipolleschi

Differential Revision: D36627043

Pulled By: f-meloni

fbshipit-source-id: bc7ff2f463c9d7cac61d362440858945edfbdbaf

.github/workflows/danger_pr.yml

@@ -12,7 +12,8 @@ jobs:
       - run: yarn install
         working-directory: bots
       - name: Danger
-        run: yarn danger ci --use-github-checks --failOnErrors --id danger_pr
+        run: DANGER_GITHUB_API_TOKEN="$PUBLIC_PULLBOT_GITHUB_TOKEN_A""$PUBLIC_PULLBOT_GITHUB_TOKEN_B" yarn danger ci --use-github-checks --failOnErrors --id danger_pr
         working-directory: bots
         env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          PUBLIC_PULLBOT_GITHUB_TOKEN_A: a6edf8e8d40ce4e8b11a
+          PUBLIC_PULLBOT_GITHUB_TOKEN_B: 150e1341f4dd9c944d2a