Add sttp 3.6.1 artifact migrations

[hugo-vrijswijk]

In sttp 3.6.1 some artifacts are no longer published as they're included in their respective 'core' modules (httpclient-backend-fs2 ➡ fs2). Example of the rename that needs to be done: https://github.com/stryker-mutator/stryker4s/pull/1154/files

This PR adds artifact migrations for the changed modules.

I haven't found a setting for what version the artifact is migrated, so I assume scala-steward uses the latest version when upgrading?

[codecov]

Codecov Report

Merging #2598 (0c151d0) into main (d44ce02) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #2598   +/-   ##
=======================================
  Coverage   81.08%   81.08%           
=======================================
  Files         144      144           
  Lines        2538     2538           
  Branches       46       46           
=======================================
  Hits         2058     2058           
  Misses        480      480           

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[hugo-vrijswijk]

@fthomas could you have a look at this 🙏?