[ci] fix R Hub token

[jameslamb]

I'm so sorry, @StrikerRUS you were absolutely right in https://github.com/microsoft/LightGBM/pull/5159#issuecomment-1124339616...the way I manually submitted the R package to R Hub yesterday, I overwrite this project's R Hub authentication token.

I had thought that a given email could have multiple auth tokens with R Hub, but I see now that that's not correct. When I tried submitting today with the existing token in .ci/run_rhub_solaris_checks.R, rhub::check() failed with the following error.

─  Uploading package
Error in query("SUBMIT PACKAGE", data = list(email = unbox(email), token = unbox(email_get_token(email)),  : 
  Email address not validated

This PR proposes updating that script with the token from #5159 (comment).

[StrikerRUS]

Oh, no problem! That wasn't obvious at all from R Hub docs!

Thanks for updating the token.

[github-actions]

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