Bump mockito-core from 4.6.1 to 4.8.1

Bumps [mockito-core](https://github.com/mockito/mockito) from 4.6.1 to 4.8.1.
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v4.6.1...v4.8.1)

---
updated-dependencies:
- dependency-name: org.mockito:mockito-core
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

app/build.gradle

@@ -53,7 +53,7 @@ dependencies {
     implementation 'com.google.firebase:firebase-messaging:23.1.0'
     // Tests
     testImplementation 'junit:junit:4.13.2'
-    testImplementation 'org.mockito:mockito-core:4.6.1'
+    testImplementation 'org.mockito:mockito-core:4.8.1'
     testImplementation 'com.squareup.okhttp3:mockwebserver:4.10.0'
     testImplementation 'org.json:json:20220320'
 }