chore(deps): update mockito monorepo to v5.21.0

Author: renovate[bot]

pom.xml

@@ -40,7 +40,7 @@
         <version.spotless>3.0.0</version.spotless>
         <version.google-java-format>1.22.0</version.google-java-format>
         <version.junit>6.0.0</version.junit>
-        <version.mockito>5.20.0</version.mockito>
+        <version.mockito>5.21.0</version.mockito>
         <version.assertj>3.27.6</version.assertj>
     </properties>