Warning about experimental directives accepting no arguments contains garbage

[alexarchambault]

Version(s)
1.0.4

Describe the bug
When compiling a project with an experimental directive accepting no argument, such as //> using python, Scala CLI prints

The `//> using python "<EmptyValue>"` directive is experimental.

The "<EmptyValue>" part is superfluous, and shouldn't be printed.

To Reproduce

$ scala-cli compile -e '//> using python
object Foo'
The `//> using python "<EmptyValue>"` directive is experimental.
Please bear in mind that non-ideal user experience should be expected.
If you encounter any bugs or have feedback to share, make sure to reach out to the maintenance team at https://github.com/VirtusLab/scala-cli
Compiling project (Scala 3.3.0, JVM)
Compiled project (Scala 3.3.0, JVM)

Expected behaviour
Scala CLI doesn't print "<EmptyValue>", like

The `//> using python` directive is experimental.