Remove archived {survMisc} from Suggests

[jdblischak]

Close #359

• The {survMisc} package continues to be archived on CRAN, and no development has occurred in the upstream repository in years
• Our previous fix focused on the immediate problem of restoring our GitHub Actions pipelines (Install survMisc from GitHub since it was archived on CRAN #361)
• But we will be unable to submit to CRAN as long as we have an archived package listed in Suggests, which I confirmed by submitting to winbuilder:

  Suggests or Enhances not in mainstream repositories:
    survMisc
  

• This PR attempts to enable a future CRAN submission while continuing to run the existing tests that require {survMisc} by using the Config/Needs approach of {remotes}, which is supported by r-lib/actions/setup-r-dependencies
• I confirmed in GitHub Actions run on my fork that {survMisc} is installed, eg here

Thoughts on this approach? Does Config/Needs/tests work or should we choose a different designation?

[yihui]

This approach sounds good to me.