Don't warn about rhino class in proguard

Likely related to 01a7b20655 but I am not completely sure.
I tested the app and it works well, so I think that org.mozilla.javascript.JavaToJSONConverters is not used really.

This is the full list of errors:
Missing class java.beans.BeanDescriptor (referenced from: java.lang.Object org.mozilla.javascript.JavaToJSONConverters.lambda$static$4(java.lang.Object))
Missing class java.beans.BeanInfo (referenced from: java.lang.Object org.mozilla.javascript.JavaToJSONConverters.lambda$static$4(java.lang.Object))
Missing class java.beans.IntrospectionException (referenced from: java.lang.Object org.mozilla.javascript.JavaToJSONConverters.lambda$static$4(java.lang.Object))
Missing class java.beans.Introspector (referenced from: java.lang.Object org.mozilla.javascript.JavaToJSONConverters.lambda$static$4(java.lang.Object))
Missing class java.beans.PropertyDescriptor (referenced from: java.lang.Object org.mozilla.javascript.JavaToJSONConverters.lambda$static$4(java.lang.Object))

app/build.gradle

@@ -56,6 +56,9 @@ android {
                 resValue "string", "app_name", "NewPipe " + System.getProperty('packageSuffix')
                 archivesBaseName = 'NewPipe_' + System.getProperty('packageSuffix')
             }
+            applicationIdSuffix ".whatever"
+            resValue "string", "app_name", "NewPipe whatever"
+            archivesBaseName = 'NewPipe_whatever'
             minifyEnabled true
             shrinkResources false // disabled to fix F-Droid's reproducible build
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'

app/proguard-rules.pro

@@ -7,6 +7,7 @@
 -keep class org.schabi.newpipe.extractor.timeago.patterns.** { *; }
 -keep class org.mozilla.javascript.** { *; }
 -keep class org.mozilla.classfile.ClassFileWriter
+-dontwarn org.mozilla.javascript.JavaToJSONConverters
 -dontwarn org.mozilla.javascript.tools.**
 
 ## Rules for ExoPlayer