Use magrittr pipe exclusively in examples for consistency

[jdblischak]

The R CMD build results for R-devel now include the following warning:

  NB: this package now depends on R (>= 4.1.0)
  WARNING: Added dependency on R >= 4.1.0 because package code uses the
  pipe |> or function shorthand \(...) syntax added in R 4.1.0.
  File(s) using such syntax:
    ‘gs_update_ahr.Rd’ ‘to_integer.Rd’

This is because we have started to use the native pipe |> in some of the examples, but the DESCRIPTION continues to only require R >=3.5:

gsDesign2/DESCRIPTION

Line 37 in d0a5897

R (>= 3.5.0)

Given that {gsDesign2} depends on dplyr and imports the magrittr pipe (%>%) into the package namespace, I think it makes sense to continue to use the magritter pipe for now:

gsDesign2/NAMESPACE

Line 68 in d0a5897

importFrom(dplyr,"%>%")

At some point we'll want to migrate the entire package to use the native pipe |>, but at this point I don't think this is urgently needed.

Background:

• {simtrial} has migrated to the native pipe and requires R >= 4.1.0 (Use base pipe operator simtrial#146). This makes more sense since it allowed us to completely drop the dependency on magrittr (since gsDesign2 depends on dplyr, magrittr will continue to be a transitive dependency whether or not we use its pipe in our code)
• The gsDesign2 README uses the native pipe (Improve readme code example #348). This is fine since this code is not run during installation and thus does not prevent the package from being built and installed with R 3.5 (and therefore R CMD check does not flag this code as problematic)

[nanxstats]

I agree with your evaluation

[LittleBeannie]

Thanks for catching these, @jdblischak!