Making the demo app hardware accelerated to better render the decibels graph

app/src/main/AndroidManifest.xml

@@ -13,6 +13,7 @@
         android:label="@string/app_name"
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
+        android:hardwareAccelerated="true"
         android:theme="@style/AppTheme">
         <activity android:name="com.mozilla.speechapp.MainActivity">
             <intent-filter>