Bump test dependencies

Author: acogoluegnes

build.gradle

@@ -34,7 +34,7 @@ ext {
 
 	// Logging
 	slf4jVersion = '1.7.30'
-	logbackVersion = '1.2.3'
+	logbackVersion = '1.2.6'
 
 	// Libraries
 	rabbitMqJavaClientVersion = '5.11.0'
@@ -45,9 +45,9 @@ ext {
 
 	// Testing
 	mockitoVersion = '3.7.7'
-	junitPlatformVersion = '1.7.0'
-	junitJupiterVersion  = '5.7.1'
-	assertjVersion = '3.19.0'
+	junitPlatformVersion = '1.8.1'
+	junitJupiterVersion  = '5.8.1'
+	assertjVersion = '3.21.0'
 
 	javadocLinks = ["https://docs.oracle.com/javase/8/docs/api/",
 					"https://www.reactive-streams.org/reactive-streams-1.0.3-javadoc/",