[ci] Fix comment in iwyu.yml

Comments need to be properly indented.

Author: gruenich

.github/workflows/iwyu.yml

@@ -21,11 +21,11 @@ jobs:
             image: "fedora:latest"
             stdlib: libstdc++
             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'
+            # 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