Make rx.Upload a memoization leaf

[ElijahAhianyo]

Simple fix to get the code below working:

rx.upload(
            rx.text("Drag and drop files here or click to select files"),
            rx.text("Selected: "),
            rx.foreach(rx.selected_files("upload3"), rx.text),
            id="upload3",
            border="1px dotted rgb(107,99,246)",
            padding="5em",
        ),