scripted-diff: Use std::span over Span

-BEGIN VERIFY SCRIPT-

 ren() { sed -i "s!\<$1\>!$2!g" $( git grep -l "$1" -- "./src" ":(exclude)src/span.h" ":(exclude)src/leveldb/db/log_test.cc" ) ; }

 ren Span            std::span
 ren AsBytes         std::as_bytes
 ren AsWritableBytes std::as_writable_bytes

 sed -i 's!SpanPopBack(Span!SpanPopBack(std::span!g' ./src/span.h

-END VERIFY SCRIPT-

src/crypto/hex_base.cpp

@@ -26,7 +26,7 @@ constexpr std::array<ByteAsHex, 256> CreateByteToHexMap()
 
 } // namespace
 
-std::string HexStr(const Span<const uint8_t> s)
+std::string HexStr(const std::span<const uint8_t> s)
 {
     std::string rv(s.size() * 2, '\0');
     static constexpr auto byte_to_hex = CreateByteToHexMap();