Figure out where the WARNINGs and NOTEs in R CMD check are coming from

[IndrajeetPatil]

These issues, seen on GHA, are coming from somewhere upstream. Difficult to diagnose from where since I can't reproduce this behaviour locally.

The CRAN version is definitely not affected, but creating an issue just as a reminder to ourselves. My guess is that this is most likely going to resolve itself in time, but will keep an eye out for it.

❯ checking tests ...
  See below...

❯ checking for code/documentation mismatches ... WARNING
  Warning in register() :
    Can't find generic `scale_type` in package ggplot2 to register S3 method.

❯ checking dependencies in R code ... NOTE
  Warning in register() :
    Can't find generic `scale_type` in package ggplot2 to register S3 method.

❯ checking foreign function calls ... NOTE
  Warning in register() :
    Can't find generic `scale_type` in package ggplot2 to register S3 method.
  See chapter ‘System and foreign language interfaces’ in the ‘Writing R
  Extensions’ manual.

❯ checking R code for possible problems ... NOTE
  Warning in register() :
    Can't find generic `scale_type` in package ggplot2 to register S3 method.
  Warning in register() :
    Can't find generic `scale_type` in package ggplot2 to register S3 method.
  
  Warning in register() :
    Can't find generic `scale_type` in package ggplot2 to register S3 method.

── Test failures ───────────────────────────────────────────────── testthat ────

> library(testthat)
> library(ggsignif)
> 
> test_check("ggsignif")
Starting 2 test processes
[ FAIL 4 | WARN 0 | SKIP 0 | PASS 11 ]

══ Failed tests ════════════════════════════════════════════════════════════════
── Error (???): (code run outside of `test_that()`) ────────────────────────────
Error: Error: 'type_sum' is not an exported object from 'namespace:pillar'
── Error (test-geom_signific_strict.R:1:1): the plotting works - strict test ───
Error: Error: 'type_sum' is not an exported object from 'namespace:pillar'
── Error (???): (code run outside of `test_that()`) ────────────────────────────
Error: Error: 'type_sum' is not an exported object from 'namespace:pillar'
── Error (test-vdiffr.R:1:1): plots are rendered correctly ─────────────────────
Error: Error: 'type_sum' is not an exported object from 'namespace:pillar'

[ FAIL 4 | WARN 0 | SKIP 0 | PASS 11 ]
Error: Error: Test failures
Execution halted

Error: Error: R CMD check found ERRORs

[IndrajeetPatil]

pillar 1.7.0 fixes this issue:
https://cran.r-project.org/web/packages/pillar/news/news.html