Fix comment reference to cpp `std::string_view`

PiperOrigin-RevId: 672926915

rust/upb/string_view.rs

@@ -7,11 +7,11 @@
 
 /// ABI compatible struct with upb_StringView.
 ///
-/// Note that this has semantics similar to `core::string_view` in C++ and
+/// Note that this has semantics similar to `std::string_view` in C++ and
 /// `&[u8]` in Rust, but is not ABI-compatible with either.
 ///
 /// If `len` is 0, then `ptr` is allowed to be either null or dangling. C++
-/// considers a dangling 0-len `core::string_view` to be invalid, and Rust
+/// considers a dangling 0-len `std::string_view` to be invalid, and Rust
 /// considers a `&[u8]` with a null data pointer to be invalid.
 #[repr(C)]
 #[derive(Copy, Clone)]