feat(overmind-svelte): conform to new API

BREAKING CHANGE:
requires new Overmind version

Author: christianalfoni

packages/node_modules/overmind-svelte/src/index.ts

@@ -11,7 +11,7 @@ export function createMixin(overmind) {
   let currentFlushId = 0
 
   const subscribe = (listener) => {
-    const tree = overmind.proxyStateTree.getTrackStateTree()
+    const tree = overmind.proxyStateTreeInstance.getTrackStateTree()
     const componentInstanceId = nextComponentInstanceId++
     let isUpdating = false
 
@@ -57,7 +57,7 @@ export function createMixin(overmind) {
     }
 
     return () => {
-      overmind.proxyStateTree.disposeTree(tree)
+      overmind.proxyStateTreeInstance.disposeTree(tree)
       overmind.eventHub.emitAsync(EventType.COMPONENT_REMOVE, {
         componentId,
         componentInstanceId: componentInstanceId,