remove pingr dependency

[Adafede]

Prework

• I understand and agree to the code of conduct and the contributing guidelines.
• I have already submitted a discussion topic or issue to discuss my idea with the maintainer.

Related GitHub issues and pull requests

• Ref: [ideas] Remove `pingr`dependency to help making `tar_watch` WASM compatible #1317

Summary

Hi @wlandau,

I try to solve the request raised in the above mentionned discussion.

[wlandau]

The general approach here is great, not just for WASM, but also to shorten the long dependency list just a little bit. I implemented this in 409f991 with minor alterations and credited you in the NEWS.md file.

[hadley]

IMO a slightly clearer style here is something like:

tryCatch(
  {
    con <- suppressWarnings(socketConnection(host, port, open = "r"))
    close(con)
    TRUE
  },
  error = function(cnd) {
    FALSE
  }
)

(And note that this still won't work in webR)

[wlandau]

(And note that this still won't work in webR)

That seems okay because tar_watch() itself is only meant to be run locally. shinylive apps will be using the module in tar_watch_ui() and tar_watch_server(), which do not use pingr. (Although until today tar_watch_ui() and tar_watch_server() did still enforce all the same dependencies as tar_watch(), including pingr, which was an oversimplification.)