Remove unused request install package permission

Unused for this build flavor and also prevents further app update submissions

Author: wax911

app/src/main/AndroidManifest.xml

@@ -8,7 +8,6 @@
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
     <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
-    <uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES" />
     <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
 
     <uses-sdk tools:overrideLibrary="io.wax911.emojify, io.wax911.support.markdown" />