Bump gradle from 4.1.3 to 4.2.1

Signed-off-by: dependabot[bot] <support@github.com>

build.gradle

@@ -18,7 +18,7 @@ buildscript {
         mavenCentral()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:4.2.0'
+        classpath 'com.android.tools.build:gradle:4.2.1'
         classpath 'com.hiya:jacoco-android:0.2'
         classpath 'gradle.plugin.com.github.spotbugs.snom:spotbugs-gradle-plugin:4.7.1'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"