Update dependency org.robolectric:robolectric to v4.15

Author: renovate[bot]

gradle/libs.versions.toml

@@ -48,7 +48,7 @@ play-core-ktx = "com.google.android.play:core-ktx:1.8.1"
 licenses = "com.google.android.gms:play-services-oss-licenses:17.1.0"
 
 junit = "junit:junit:4.13.2"
-robolectric = "org.robolectric:robolectric:4.14.1"
+robolectric = "org.robolectric:robolectric:4.15"
 
 [plugins]
 androidGradlePlugin = { id = "com.android.application", version.ref = "androidGradlePlugin" }