scripted-diff: Use UniValue.pushKV instead of push_back(Pair())

-BEGIN VERIFY SCRIPT-
git grep -l "push_back(Pair" | xargs sed -i "s/push_back(Pair(\(.*\)));/pushKV(\1);/g"
-END VERIFY SCRIPT-

src/wallet/rpcdump.cpp

@@ -790,7 +790,7 @@ UniValue dumpwallet(const JSONRPCRequest& request)
     file.close();
 
     UniValue reply(UniValue::VOBJ);
-    reply.push_back(Pair("filename", filepath.string()));
+    reply.pushKV("filename", filepath.string());
 
     return reply;
 }