setup-macos: Disable installation of imagemagick

It is failing with the following error message:

  ==> imagemagick
  imagemagick-full includes additional tools and libraries that are not
  included in the regular imagemagick formula.

Fixes #3172.

Author: wantehchang

.github/actions/setup-macos/action.yml

@@ -60,6 +60,7 @@ runs:
     - name: Install imagemagick
       # imagemagick is used in sh tests (not gtest tests) but we assume that no tests are run by the CI
       # if gtest is off
+      # TODO: issue #3172 - Disable temporarily.
       if: ${{ inputs.gtest != 'OFF' }}
       run: echo "AVIF_MAC_LIBRARIES=${{ env.AVIF_MAC_LIBRARIES }} imagemagick" >> "$GITHUB_ENV"
       shell: bash