Remove {styler} dependency

[lorenzwalthert]

Hi, author of the formatting package {styler} here. As I judge from a search in your source code, there is no functionality that uses {styler}, in other words {styler} is not a runtime dependency. It's only used in your test that setup to deactivate the cache (I don't know why you use it there), so it's currently a test dependency. Adding {styler} as a dependency (via Imports: or Suggests:) to your package has the following drawbacks:

• Your user's may install a package they don't need (assuming most people who install your package are useres, not developers). This costs additional bandwith, installation time, disk space etc... If they need it, they can just manually install it.
• I as a maintainer of {styler} have to run reverse dependency checks (R CMD Check your package with my new version of {styler}) upon submitting to CRAN e.g. with {revdepcheck}. {styler} has more than 40 reverse dependencies, which makes this a long process.

For that reason, I suggest you to drop that dependency from your package. I.e. remove that styler::cache_deactivate() call that I don't get why it's there). If you want to ensure your code remains styled, I recommend {precommit} to apply {styler} on each commit or other tools described in the third-party integrations website of {styler}.

For the removal to take effect, a CRAN submission of your package is required (but the issue is not urgent). For tracking, this issue is referenced in r-lib/styler#1121.