Try using LLVM 18 instead of Apple Clang

Signed-off-by: Julien Jerphanion <git@jjerphan.xyz>

.github/workflows/osx.yml

@@ -25,6 +25,16 @@ jobs:
 
  steps:
 
+ - name: Set up LLVM 16
+ uses: actions/setup-llvm@v2
+ run: |
+ echo "CC=clang" >> $GITHUB_ENV
+ echo "CXX=clang++" >> $GITHUB_ENV
+ with:
+ # The version of LLVM we use is the one present on conda-forge.
+ # See: https://github.com/conda-forge/conda-forge-pinning-feedstock/blob/main/recipe/conda_build_config.yaml#L32
+ llvm-version: 16
+
  - name: Checkout code
  uses: actions/checkout@v3