macOS package: fix warning about supported Octave version

In 0c77f7e9, the supported Octave version has
been changed from the Homebrew binary to the standalone application.

However, the runtime check about the supported Octave version was not updated,
and was still pointing to the Homebrew version number.
9 jobs for 4.6 in 303 minutes and 20 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Build
passed #18446
build_binaries

00:11:54

passed #18447
build_doc

00:01:04

 
  Test And Pkg
passed #18450
macOS
pkg_macOS

00:12:13

passed #18448
pkg_source

00:02:07

passed #18449
pkg_windows

00:27:38

passed #18454
test_dynare++

00:11:37

passed #18451
test_matlab

01:23:15

passed #18453
test_octave

04:21:39

passed #18452
test_old_matlab

01:10:21