CI: Remove macOS testing

This appears to be too flaky and also the costs is 10x higher then
running it on Ubuntu.

Author: nodeg

.github/workflows/test.yml

@@ -36,10 +36,6 @@ jobs:
         os: [ubuntu-latest]
         # Due to https://github.com/actions/runner/issues/849, we have to use quotes for '3.0'
         ruby: ['3.4', '4.0']
-        include:
-          # Necessary for testing the different shell and sub-shell behavior
-          - os: macos-latest
-            ruby: '4.0'
     runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout