[skip ci] Try to fix fuzz ci

.github/workflows/fuzz.yml

@@ -34,14 +34,10 @@ jobs:
     env:
       CC: clang
       CXX: clang++
-      CXXFLAGS: -stdlib=libc++
 
     steps:
       - uses: actions/checkout@v1
 
-      - uses: friendlyanon/fetch-core-count@v1
-        id: cores
-
       - name: Install dependencies
         run: |
           apt-get update