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/test/miniscript_tests.cpp

@@ -272,7 +272,7 @@ public:
         return sig == it->second;
     }
 
-    bool CheckSchnorrSignature(Span<const unsigned char> sig, Span<const unsigned char> pubkey, SigVersion,
+    bool CheckSchnorrSignature(std::span<const unsigned char> sig, std::span<const unsigned char> pubkey, SigVersion,
                                ScriptExecutionData&, ScriptError*) const override {
         XOnlyPubKey pk{pubkey};
         auto it = g_testdata->schnorr_signatures.find(pk);