CI-unixish.yml: fixed missing nproc on MacOS

Author: firewave

.github/workflows/CI-unixish.yml

@@ -24,6 +24,12 @@ jobs:
       run: |
           sudo apt-get update
           sudo apt-get install valgrind
+
+    # coreutils contains "nproc"
+    - name: Install missing software on macos
+      if: contains(matrix.os, 'macos')
+      run: |
+        brew install coreutils
           
     - name: make simplecpp
       run: make -j$(nproc)