Replace std::from_chars with std::strtod for floats in cli::Reader

std::from_chars for floating-point types is not available in Apple
Clang's libc++. Use std::strtod which is locale-independent by default
(uses C locale) and works on all platforms.

Author: Centimo

include/rfl/cli/Reader.hpp

@@ -3,6 +3,7 @@
 
 #include <charconv>
 #include <concepts>
+#include <cstdlib>
 #include <map>
 #include <optional>
 #include <set>
@@ -61,14 +62,13 @@ template <class T> requires (std::is_floating_point_v<T>)
 rfl::Result<T> parse_value(
     const std::string& _str, const std::string& _path
 ) noexcept {
-  T value;
-  const auto [ptr, ec] =
-      std::from_chars(_str.data(), _str.data() + _str.size(), value);
-  if (ec != std::errc() || ptr != _str.data() + _str.size()) {
+  char* end = nullptr;
+  const double value = std::strtod(_str.c_str(), &end);
+  if (end != _str.c_str() + _str.size()) {
     return error(
         "Could not cast '" + _str + "' to floating point for key '" + _path + "'.");
   }
-  return value;
+  return static_cast<T>(value);
 }
 
 template <class T> requires (std::is_integral_v<T> && !std::same_as<T, bool>)