upgrade Gradle and Android plugin (#1709)

* upgrade Gradle and Android plugin

* upgrade Android Gradle plugin to 3.6.1

build.gradle

@@ -5,7 +5,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.5.3'
+        classpath 'com.android.tools.build:gradle:3.6.1'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }

gradle.properties

@@ -15,5 +15,5 @@ org.gradle.jvmargs=-Xmx4096m
 # use parallel execution
 org.gradle.parallel=true
 
-android.enableUnitTestBinaryResources=true
 android.enableR8.fullMode=true
+android.useAndroidX=true

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.1.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.2.1-all.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists