CI: Install OMP on MacOS

Author: w1th0utnam3

.github/workflows/ci.yml

@@ -19,6 +19,10 @@ jobs:
     steps:
       - uses: actions/checkout@v6
 
+      - name: Install libomp (macOS)
+        if: runner.os == 'macOS'
+        run: brew install libomp
+
       - name: Configure CMake
         run: |
           cmake -B build \