Disable LOB(const basic_string<T> &) constructor for invalid T

This fixes compilation against libcxx 19, which removed the
specialization for std::char_traits<unsigned char>.
See https://reviews.llvm.org/D138307 and
https://reviews.llvm.org/D157058.

Closes #4722.

Data/include/Poco/Data/LOB.h

@@ -63,7 +63,9 @@ class LOB
 	{
 	}
 
-	LOB(const std::basic_string<T>& content):
+	template<typename Content = std::basic_string<T>,
+		typename = std::enable_if_t<std::is_same_v<Content, std::basic_string<T>>>>
+	LOB(const Content& content):
 		_pContent(new std::vector<T>(content.begin(), content.end()))
 		/// Creates a LOB from a string.
 	{