CI-unixish.yml: fixed missing nproc on macos-*

Author: firewave

.github/workflows/CI-unixish.yml

@@ -41,6 +41,12 @@ jobs:
         sudo apt-get update
         sudo apt-get install libc++-18-dev
 
+      # coreutils contains "nproc"
+    - name: Install missing software on macos
+      if: contains(matrix.os, 'macos')
+      run: |
+        brew install coreutils
+
     - name: Install missing software on macos
       if: contains(matrix.os, 'macos')
       run: |