allow unencrypted http on android 9

this commit is just to make policies equal and independent on various android
versions. support for http might be removed in the future across all versions.

src/main/res/xml/network_security_configuration.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <network-security-config>
-    <base-config>
+    <base-config cleartextTrafficPermitted="true">
         <trust-anchors>
             <certificates src="system" />
             <certificates src="user" />