update string_view lite to version 1.8.0 (#2197)

This is the header as seen for the tag v1.8.0,
commit a47222b9855dd6e6d1eac38acaa495822e2caa69, on
<https://github.com/martinmoene/string-view-lite>.

include/simdjson/nonstd/string_view.hpp

@@ -6,13 +6,13 @@
 // Distributed under the Boost Software License, Version 1.0.
 // (See accompanying file LICENSE.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
-// #pragma once // We remove #pragma once here as it generates a warning in some cases. We rely on the include guard.
+#pragma once
 
 #ifndef NONSTD_SV_LITE_H_INCLUDED
 #define NONSTD_SV_LITE_H_INCLUDED
 
 #define string_view_lite_MAJOR  1
-#define string_view_lite_MINOR  7
+#define string_view_lite_MINOR  8
 #define string_view_lite_PATCH  0
 
 #define string_view_lite_VERSION  nssv_STRINGIFY(string_view_lite_MAJOR) "." nssv_STRINGIFY(string_view_lite_MINOR) "." nssv_STRINGIFY(string_view_lite_PATCH)
@@ -134,6 +134,8 @@
 
 #if nssv_CONFIG_CONVERSION_STD_STRING_FREE_FUNCTIONS
 
+#include <string>
+
 namespace nonstd {
 
 template< class CharT, class Traits, class Allocator = std::allocator<CharT> >