clang-tidy: ignore the use-trailing-return-type lint

CMake isn't ready for this yet.

.clang-tidy

@@ -13,6 +13,7 @@ modernize-*,\
 -modernize-avoid-c-arrays,\
 -modernize-use-nodiscard,\
 -modernize-use-noexcept,\
+-modernize-use-trailing-return-type,\
 -modernize-use-transparent-functors,\
 performance-*,\
 readability-*,\