Fix Range.h to compile in c++20 (#1542)

Summary:
`std::is_pod` is deprecated in c++20, using `is_trivially_copyable` instead

Pull Request resolved: https://github.com/facebook/folly/pull/1542

Reviewed By: Mizuchi

Differential Revision: D27214088

Pulled By: yfeldblum

fbshipit-source-id: 3cc6e29e16a1568cf1e9bbb73152e7bc2179f5d6

folly/Range.h

@@ -474,7 +474,7 @@ class Range {
   template <typename ValueType>
   struct StringViewType
       : std::conditional<
-            std::is_pod<std::remove_const_t<ValueType>>::value,
+            std::is_trivial<std::remove_const_t<ValueType>>::value,
             std::basic_string_view<std::remove_const_t<ValueType>>,
             NotStringView> {};