bump kangaroo version

Author: matthme

kangaroo.config.ts

@@ -3,7 +3,7 @@ import { defineConfig } from './src/main/defineConfig';
 export default defineConfig({
   appId: 'org.holochain.kangaroo-electron',
   productName: 'Holochain Kangaroo Electron',
-  version: '0.3.0-rc.3',
+  version: '0.3.0',
   macOSCodeSigning: false,
   windowsEVCodeSigning: false,
   fallbackToIndexHtml: true,