Skip this test on CRAN because it can call GitHib

Depending on what else has happened recently from same IP address, one can hit a rate limit.

Right after v2.1.2 was first accepted, I was notified by Professor Brian Ripley of this (flavor was r-devel-linux-x86_64-fedora-clang):

 ══ Failed tests ════════════════════════════════════════════════════════════════
     ── Error (test-tidyverse.R:22:3): use_tidy_dependencies() isn't overly informative ──
     `use_tidy_dependencies()` threw an unexpected error.
     Message:
     GitHub API error (403):
     Message: API rate limit exceeded for 163.1.211.17. (But here's the good news: Authenticated requests get a higher rate limit. Check out the documentation for more details.)
     Read more at https://docs.github.com/rest/overview/resources-in-the-rest-api#rate-limiting
     Class: github_error/http_error_403/error/condition

     [ FAIL 1 | WARN 0 | SKIP 36 | PASS 643 ]

Author: jennybc

tests/testthat/test-tidyverse.R

@@ -14,6 +14,7 @@ test_that("use_tidy_description() alphabetises dependencies and remotes", {
 
 test_that("use_tidy_dependencies() isn't overly informative", {
   skip_if_offline()
+  skip_on_cran()
 
   create_local_package(fs::path_temp("tidydeps"))
   use_package_doc()