gradle: Upgrade robolectric and add explicit dependency on hamcrest

Current hamcrest dependency was coming from robolectric but upgrading it
removed it.

Signed-off-by: Aayush Gupta <aayushgupta219@gmail.com>
diff --git a/app/build.gradle b/app/build.gradle
index 09291b0..d976a9f 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -138,10 +138,11 @@
     // anything less than 'implementation' fails tests run with gradlew
     testImplementation rootProject.ext.aosp_libs
     testImplementation 'androidx.test.ext:junit:1.1.3'
-    testImplementation('org.robolectric:robolectric:4.3.1') { // 4.4 has issue with non-idle Looper
+    testImplementation('org.robolectric:robolectric:4.8.1') {
         // https://github.com/robolectric/robolectric/issues/5245
         exclude group: "com.google.auto.service", module: "auto-service"
     }
+    testImplementation 'org.hamcrest:hamcrest:2.2'
     testImplementation "org.junit.jupiter:junit-jupiter-api:$junit5_version"
     testImplementation "org.junit.jupiter:junit-jupiter-params:$junit5_version"
     testImplementation "io.mockk:mockk:$mockk_version"