[R-SIG-Mac] R-latest.pkg link returning a 403 Forbidden error

[Jim Hester]

The link https://mac.r-project.org/bin/macosx/R-latest.pkg which
previously served the latest version of R is now returning a 403. Is
this an intentional change, or is it an unintentional? This link is
used by the Travis-CI build scripts for macOS, so if the link is no
longer valid we will need to update the script.

Thanks,

Jim