message: Fix events _only_ being observed when the subscriber disables them
diff: @@ -337,7 +337,7 @@ impl<'a> Event<'a> {
  /// [`Callsite`]: ::callsite::Callsite
  pub fn observe(
  callsite: &'a dyn callsite::Callsite,
  - field_values: &[&dyn field::AsValue],
  + field_values: &[&dyn field::Value],
  follows_from: &[SpanId],
  message: fmt::Arguments<'a>,
  ) {
  @@ -348,6 +348,8 @@ impl<'a> Event<'a> {
  Dispatch::with_current(|dispatch| {
  let meta = callsite.metadata();
  if interest == Interest::SOMETIMES && !dispatch.enabled(meta) {
  + return;
  + }
  dispatch.observe_event(&Event {
  parent: SpanId::current(),
  follows_from,
  @@ -355,7 +357,6 @@ impl<'a> Event<'a> {
  field_values,
  message,
  });
  - }
  })
  }
  