add visR namespace to step_ribbon function call re issue #449

[bailliem]

What changes are proposed in this pull request?

Add visR namespace to step_ribbon function call.
Add experimental lifecycle to current version of add_CI() due to extension with ribbon.

Which files are involved in this pull request and what changes were made?

• add_CI.R
• stat_stepribbon.R

Did you include unit tests for the proposed change/bug fix (https://testthat.r-lib.org/)?

Add this to issue #443

If there is an GitHub issue associated with this pull request, please provide link.

#449

Checklist for PR reviewer

• PR branch has pulled the most recent updates from main branch. Ensure the pull request branch and your local version match and both have the latest updates from the main branch.
• If a new function was added, function should be included in _pkgdown.yml
• If a bug was fixed, a unit test was added for the bug check
• Run pkgdown::build_site(). Check the R console for errors, and review the rendered website.
• Code coverage is suitable for any new functions/features. Review coverage with withr::with_envvar(new = c("NOT_CRAN" = "true"), covr::report()). Before you run, begin a fresh R session without any packages loaded.
• R CMD Check runs without errors, warnings, and notes
• usethis::use_spell_check() runs with no spelling errors in documentation
• Has NEWS.md been updated with the changes from this pull request under the heading indicating the latest version. If there is an issue associated with the pull request, reference it in parentheses at the end update (see NEWS.md for examples).
• Has the version number been incremented using usethis::use_version(which = "dev")
• Run devtools::build_readme() to build the README.md file.
• Approve Pull Request
• Merge the PR. Please use "Squash and merge".

[bailliem]

checked