dfshrink 0.1.2

Changed

• The release pipeline now install-tests the source distribution and every
  supported Python version, and retries transient network failures instead of
  failing outright.
• Releases now post the versioned changelog section as GitHub release notes
  automatically.
• CI builds the package once per dry-run job and shares a single "open an
  issue on failure" workflow between the matrix and scheduled checks.