aml: fix breakage by not deriving `Debug` on `AmlContext`

`AmlContext` can't derive `Debug` because we don't require the `Handler`
to be `Debug`. We could do this with a custom implementation but I don't
think there's much point; the state of the context is not super useful when
you can just access the children.

Unfortunately this change was made by a PR that clearly was not tested to
compile (irritating), and then not caught by CI because it broke months ago
when we renamed `master` to `main` :(

aml/src/lib.rs

@@ -109,7 +109,6 @@ impl MethodContext {
     }
 }
 
-#[derive(Debug)]
 pub struct AmlContext {
     /// The `Handler` passed from the library user. This is stored as a boxed trait object simply to avoid having
     /// to add a lifetime and type parameter to `AmlContext`, as they would massively complicate the parser types.