fixes bad binding in event listener

deno.json

@@ -1,6 +1,6 @@
 {
   "name": "@bearmetal/store",
-  "version": "0.0.3",
+  "version": "0.0.5",
   "description": "A simple store for storing data in a JSON file.",
   "files": [
     "mod.ts",

store.ts

@@ -76,9 +76,9 @@ export class BearMetalStore {
     this.writeOut();
   }
 
-  private readIn() {
+  private readIn = () => {
     this.store = JSON.parse(Deno.readTextFileSync(this.storePath) || "{}");
-  }
+  };
 
   private writeOut() {
     Deno.writeTextFileSync(this.storePath, JSON.stringify(this.store));