PR Benchmark Bot GH creds failure

[CarnaViire]

Error on publishing comments, e.g. with benchmark results (log)

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Publishing results
An error occurred: Octokit.AuthorizationException: Bad credentials
   at Octokit.Connection.HandleErrors(IResponse response) in /_/Octokit/Http/Connection.cs:line 785
   at Octokit.Connection.RunRequest(IRequest request, CancellationToken cancellationToken, Func`2 preprocessResponseBody) in /_/Octokit/Http/Connection.cs:line 766
   at Octokit.Connection.Run[T](IRequest request, CancellationToken cancellationToken, Func`2 preprocessResponseBody) in /_/Octokit/Http/Connection.cs:line 751
   at Octokit.ApiConnection.Post[T](Uri uri, Object data, String accepts, String contentType, CancellationToken cancellationToken)
   at Microsoft.Crank.PullRequestBot.Program.Controller(BotOptions options) in D:\a\_work\1\crank\src\Microsoft.Crank.PullRequestBot\Program.cs:line 348
{"message":"Bad credentials","documentation_url":"[https://docs.github.com/rest"}](https://docs.github.com/rest%22%7D)
Unhandled exception: Octokit.AuthorizationException: Bad credentials
   at Octokit.Connection.HandleErrors(IResponse response) in /_/Octokit/Http/Connection.cs:line 785
...