Maps to
[`CXCursor_ConceptDecl`](ee8524087c/clang/include/clang-c/Index.h (L2716)),
added in ee8524087c78a673fcf5486ded69ee597a85e0f1.
Without this I get this error on my codebase which uses C++20 concept
decls:
```
ValueError: Unknown template argument kind 604
```