Include mockito as test dependency

pgpainless-core/build.gradle

@@ -12,6 +12,9 @@ dependencies {
     testImplementation "org.junit.jupiter:junit-jupiter-params:$junitVersion"
     testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:$junitVersion"
 
+    // Mocking Components
+    testImplementation "org.mockito:mockito-core:$mockitoVersion"
+
     // Logging
     api "org.slf4j:slf4j-api:$slf4jVersion"
     testImplementation "ch.qos.logback:logback-classic:$logbackVersion"

version.gradle

@@ -9,9 +9,10 @@ allprojects {
         pgpainlessMinAndroidSdk = 10
         javaSourceCompatibility = 1.8
         bouncyCastleVersion = '1.71'
-        slf4jVersion = '1.7.36'
-        logbackVersion = '1.2.11'
         junitVersion = '5.8.2'
+        logbackVersion = '1.2.11'
+        mockitoVersion = '4.5.1'
+        slf4jVersion = '1.7.36'
         sopJavaVersion = '4.0.0'
     }
 }