Upgrade AssertJ to 3.21.0 and other test dependencies

fixes gh-2826

Author: jonatan-ivanov

dependencies.gradle

@@ -64,8 +64,8 @@ def VERSIONS = [
         'org.junit.platform:junit-platform-launcher:1.7.+',
         'org.junit.vintage:junit-vintage-engine:5.7.+',
         'org.latencyutils:LatencyUtils:latest.release',
-        'org.mockito:mockito-core:latest.release',
-        'org.mockito:mockito-inline:latest.release',
+        'org.mockito:mockito-core:3.+',
+        'org.mockito:mockito-inline:3.+',
         'org.mongodb:mongo-java-driver:latest.release',
         'org.slf4j:slf4j-api:1.7.+',
         'org.springframework:spring-context:latest.release',