(clang-tidy): Disable 'modernize-use-designated-initializers'

modernize-use-designated-initializers checks for initializer lists that
could be written as designated initializers instead.
See https://clang.llvm.org/extra//clang-tidy/checks/modernize/use-designated-initializers.html

However, this is a C++20 feature. While it can be supported by compilers
before C++20, it is still enabled by default by clang-tidy.

Since designated initializers are not in the standard pre C++20,
and this library supports versions up to including C++20, I would
suggest disabling this check.

.clang-tidy

@@ -44,6 +44,7 @@ Checks: '*,
          -modernize-concat-nested-namespaces,
          -modernize-type-traits,
          -modernize-use-constraints,
+         -modernize-use-designated-initializers,
          -modernize-use-nodiscard,
          -modernize-use-trailing-return-type,
          -performance-enum-size,