chore: Update dependency org.mockito:mockito-core to v4 (#1360)

Co-authored-by: Renovate Bot <bot@renovateapp.com>

gradle/libs.versions.toml

@@ -51,7 +51,7 @@ text = "3.0.4"
 piston = "0.5.7"
 
 # Tests
-mockito = "3.12.4"
+mockito = "4.0.0"
 checker-qual = "3.18.1"
 
 # Gradle plugins

worldedit-sponge/build.gradle.kts

@@ -28,7 +28,7 @@ dependencies {
     })
     api("org.apache.logging.log4j:log4j-api")
     api("org.bstats:bstats-sponge:1.7")
-    testImplementation("org.mockito:mockito-core:3.11.2")
+    testImplementation("org.mockito:mockito-core:4.0.0")
 }
 
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