ci: Try to fix macOS runner

Now seems to run on arm64 out of the blue...

Author: emilio

.github/workflows/bindgen.yml

@@ -178,11 +178,8 @@ jobs:
           #   feature_extra_asserts: 0
 
           # Ensure stuff works on macos too
-          # FIXME: Ideally should use the latest llvm version, but llvm doesn't
-          # provide releases for x86-64 macOS anymore which is what the runner uses.
-          #
           - os: macos-latest
-            llvm_version: "9.0"
+            llvm_version: "16.0"
             release_build: 0
             no_default_features: 0
             feature_extra_asserts: 0