update sdk versions to API 31

tor-android-binary/build.gradle

@@ -11,12 +11,12 @@ def getVersionName = { ->
 }
 
 android {
-    compileSdkVersion 30
-    buildToolsVersion '30.0.3'
+    compileSdkVersion 31
+    buildToolsVersion '31.0.0'
 
     defaultConfig {
         minSdkVersion 16
-        targetSdkVersion 30
+        targetSdkVersion 31
         versionCode 41500
         versionName getVersionName()
 
@@ -86,7 +86,7 @@ task sourcesJar(type: Jar) {
 task javadoc(type: Javadoc) {
     source = android.sourceSets.main.java.srcDirs
     classpath += project.files(android.getBootClasspath().join(File.pathSeparator))
-    classpath += configurations.compile
+    classpath += configurations.implementation
     options.noTimestamp = true
     options.addStringOption('charset', 'UTF-8') // to match Maven's case
     android.libraryVariants.all { variant ->