Remove poster from audio content

package.json

 {
   "name": "@epoc/epoc-types",
-  "version": "2.0.0-beta.4",
+  "version": "2.0.0-beta.5",
   "description": "ePoc (Electronic Pocket Open Course) types specifications",
   "main": "dist/index.ts",
   "types": "dist/index.d.ts",

src/v1/content.ts

@@ -22,7 +22,6 @@ export interface Audio extends Content {
     source: string;
     summary: html;
     transcript: string;
-    poster: string;
 }
 
 export interface Html extends Content {

src/v2/content.ts

@@ -75,11 +75,6 @@ export interface Audio extends BaseContent {
      * Specifies the text transcript of the audio
      */
     transcript: string;
-
-    /**
-     * Specifies the video poster (thumbnail) uri
-     */
-    poster: uri;
 }
 
 /**