Upload fails for PRs from forks

[jdrueckert]

On reviewing a recent PR from a contributor on the TerasologyLauncher, I noticed that the check-run-reporter stage in one of our actions fails with the following error:

Requesting signed urls
  Error: Request ID: undefined
  Error: Response Headers: {
    'content-type': 'application/json',
    'content-length': '144',
    connection: 'close',
    date: 'Thu, 06 Apr 2023 12:27:57 GMT',
    'x-amzn-requestid': 'e523bd5e-ed56-4bc3-86d1-68772bda0d94',
    'x-amzn-errortype': 'AccessDeniedException',
    'x-amz-apigw-id': 'C9IePEo7IAMFfXA=',
    'x-amzn-trace-id': 'Root=1-642ebac1-62a3afb95a204d8c51947e21',
    'x-cache': 'Error from cloudfront',
    via: '1.1 d835a04e842d9117fd810e7c8479dad4.cloudfront.net (CloudFront)',
    'x-amz-cf-pop': 'IAD55-P2',
    'x-amz-cf-id': 'YuH_bcN-elxfiggIWGQUvLRdUDIK13Rsz2KPm6Sp3zUN-LRxIZjtig=='
  }
  Error: Response Body: {
    message: 'Authorization header appears to be malformed. The Basic auth schema requires a username and a password separated by a colon.'
  }
  Error: Request URL: /api/v1/submissions/upload
Error: Error: Request failed with status code 403
Error: Check Run Reporter returned a 403
Error: Error: Request failed with status code 403
    at createError (/home/runner/work/_actions/check-run-reporter/action/v2.11.1/node_modules/axios/lib/core/createError.js:16:1)
    at settle (/home/runner/work/_actions/check-run-reporter/action/v2.11.1/node_modules/axios/lib/core/settle.js:17:1)
    at IncomingMessage.handleStreamEnd (/home/runner/work/_actions/check-run-reporter/action/v2.11.1/node_modules/axios/lib/adapters/http.js:293:1)
    at IncomingMessage.emit (events.js:326:22)
    at endReadableNT (_stream_readable.js:1241:12)
    at processTicksAndRejections (internal/process/task_queues.js:84:21)

On creating a pull request with the same changes directly on the original repo (as opposed to from a fork), the stage completes successfully. For example, see PRs #692 (from fork) and #693 (from orig repo).

The check-run-reporter action seems to be unable to properly set the authorization header required for uploading the report.