hides Go pro button by default, shows if no subscription is received

app/src/main/res/layout/fragment_feed.xml

@@ -111,6 +111,7 @@
 
 	<com.google.android.material.button.MaterialButton
 		android:id="@+id/subscribe"
+		android:visibility="invisible"
 		android:text="@string/pro_purchase"
 		style="@style/PokerAnalyticsTheme.Button"
 		android:layout_width="wrap_content"