unable to access index for repository https://macos.rbind.org/src/contrib

I am trying to install rattle on macOS (Link):

system('brew install gtk+')

local({
  if (Sys.info()[['sysname']] != 'Darwin') return()

  .Platform$pkgType = 'mac.binary.el-capitan'
  unlockBinding('.Platform', baseenv())
  assign('.Platform', .Platform, 'package:base')
  lockBinding('.Platform', baseenv())

  options(
    pkgType = 'both', install.packages.compile.from.source = 'always',
    repos = 'https://macos.rbind.org'
  )
})

install.packages(c('RGtk2', 'cairoDevice', 'rattle'))

But I am getting the following error:

Warning in install.packages :

  unable to access index for repository https://macos.rbind.org/src/contrib:

  cannot open URL 'https://macos.rbind.org/src/contrib/PACKAGES'

Warning in install.packages :

  unable to access index for repository https://macos.rbind.org/src/contrib:

  cannot open URL 'https://macos.rbind.org/src/contrib/PACKAGES'

Warning in install.packages :

  packages ‘RGtk2’, ‘cairoDevice’, ‘rattle’ are not available (for R version 3.6.2)

Warning in install.packages :

  unable to access index for repository https://macos.rbind.org/bin/macosx/el-capitan/contrib/3.6:

  cannot open URL 'https://macos.rbind.org/bin/macosx/el-capitan/contrib/3.6/PACKAGES'

Looking at the above error, it is supersing that I see:

packages ‘RGtk2’, ‘cairoDevice’, ‘rattle’ are not available (for R version 3.6.2)

While I installed rattle on Windows based on R 3.6.2.

It would appear that macos.rbind.org is no longer active. Perhaps try macos.rbind.io. That is, replace

repos = 'https://macos.rbind.org'

with

repos = 'https://macos.rbind.io'