iwyu.yml: disabled include-what-you-use with libc++ for now [skip ci]

Author: firewave

.github/workflows/iwyu.yml

@@ -21,10 +21,11 @@ jobs:
             image: "fedora:latest"
             stdlib: libstdc++
             clang_inc: '-isystem/usr/lib/clang/20/include'
-          - os: ubuntu-22.04
-            image: "fedora:latest"
-            stdlib: libc++
-            clang_inc: '-isystem/usr/lib/clang/20/include'
+          # TODO: disable because it currently fails with "error: <cstddef> tried including <stddef.h> but didn't find libc++'s <stddef.h> header."
+          #- os: ubuntu-22.04
+          #  image: "fedora:latest"
+          #  stdlib: libc++
+          #  clang_inc: '-isystem/usr/lib/clang/20/include'
           - os: macos-13
             image: ""
             stdlib: libc++  # no libstdc++ on macOS