android: remove unused ProGuard rules file

android/sdk/proguard-rules.pro

@@ -1,25 +0,0 @@
-# Add project specific ProGuard rules here.
-# By default, the flags in this file are appended to flags specified
-# in /Users/scorretge/Library/Android/sdk/tools/proguard/proguard-android.txt
-# You can edit the include path and order by changing the proguardFiles
-# directive in build.gradle.
-#
-# For more details, see
-#   http://developer.android.com/guide/developing/tools/proguard.html
-
-# Add any project specific keep options here:
-
-# If your project uses WebView with JS, uncomment the following
-# and specify the fully qualified class name to the JavaScript interface
-# class:
-#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
-#   public *;
-#}
-
-# Uncomment this to preserve the line number information for
-# debugging stack traces.
-#-keepattributes SourceFile,LineNumberTable
-
-# If you keep the line number information, uncomment this to
-# hide the original source file name.
-#-renamesourcefileattribute SourceFile