tRakt 0.17.0

This is been well over a year of "hobby project staleness says what?", but alas, it is done(ish).

Switch from {httr} to {httr2}

This should have been a small under the hood change, but it also enabled major changes in the way I'm handling API secrets, allowing me to include my encrypted client secret with the package directly.
This should make it more convenient for users to make authenticated requests without having to register their own app on trakt.tv.

The main user-facing highlight however should probably be more stable API interactions including

• Automatic retries in case of errors (up to 3, currently not configurable)
• Caching of API results to getOption("tRakt_cache_dir"), which is pruned
  • after 1 week by default (option tRakt_cache_max_age)
  • after exceeding a total of 100MB (option tRakt_cache_max_size)

Minor changes

• Remove magrittr import and use |> internally, hence bumping the R dependency to >= 4.1.
• Clean up unused package imports.
• tRakt_sitrep() is now available to check general settings and API credentials.
• Switch to {testthat} 3e.