fix: remove methods that are incompatible with the minimal version

src/metrics.rs

@@ -415,10 +415,6 @@ impl<S> Layer<S> for MetricsLayer<S>
 where
     S: Subscriber + for<'span> LookupSpan<'span>,
 {
-    fn on_register_dispatch(&self, collector: &tracing_core::Dispatch) {
-        self.inner.on_register_dispatch(collector)
-    }
-
     fn on_layer(&mut self, subscriber: &mut S) {
         self.inner.on_layer(subscriber)
     }
@@ -462,10 +458,6 @@ where
         self.inner.on_follows_from(span, follows, ctx)
     }
 
-    fn event_enabled(&self, event: &tracing_core::Event<'_>, ctx: Context<'_, S>) -> bool {
-        self.inner.event_enabled(event, ctx)
-    }
-
     fn on_event(&self, event: &tracing_core::Event<'_>, ctx: Context<'_, S>) {
         self.inner.on_event(event, ctx)
     }