Reduce the VST2 events small vector capacities

Every DAW will just send all events in one go (and I think that's the
only way you should do it, but the VST2 spec is a bit leaky so who
knows). It wouldn't make much sense to preallocate more capacity,
because when DAWs do send all of those events individually they might
end up sending more than four of these anyways.

src/plugin/bridges/vst2.h

@@ -205,7 +205,7 @@ class Vst2PluginBridge : PluginBridge<Vst2Sockets<std::jthread>> {
      * we receive so we can send them to host on the audio thread at the end of
      * `process_replacing()`.
      */
-    boost::container::small_vector<DynamicVstEvents, 4> incoming_midi_events;
+    boost::container::small_vector<DynamicVstEvents, 1> incoming_midi_events;
     /**
      * Mutex for locking the above event queue, since recieving and processing
      * now happens in two different threads.

src/wine-host/bridges/vst2.h

@@ -201,7 +201,7 @@ class Vst2Bridge : public HostBridge {
      * practice every host will bundle all events in a single
      * `effProcessEvents()` call.
      */
-    boost::container::small_vector<DynamicVstEvents, 4>
+    boost::container::small_vector<DynamicVstEvents, 1>
         next_audio_buffer_midi_events;
     /**
      * Whether `next_audio_buffer_midi_events` should be cleared before