Fix: do not rebuild ninja when building playground

Author: cknitt

.github/workflows/ci.yml

@@ -401,6 +401,14 @@ jobs:
       #     path: ./tests/benchmark-cache
       #     key: syntax-benchmark-v1
 
+      # Prevent ninja being rebuilt on playground build step
+      - name: Touch ninja/ninja
+        if: ${{ matrix.build_playground && steps.ninja-build-cache.outputs.cache-hit == 'true' }}
+        run: |
+          ls -l ninja/ninja${{ runner.os == 'Windows' && '.exe' || '' }}
+          touch ninja/ninja${{ runner.os == 'Windows' && '.exe' || '' }}
+          ls -l ninja/ninja${{ runner.os == 'Windows' && '.exe' || '' }}
+
       - name: Build playground compiler
         if: matrix.build_playground
         run: opam exec -- make playground