Bump assertj-core from 3.20.2 to 3.21.0 (#86)

Author: dependabot[bot]

pom.xml

@@ -142,7 +142,7 @@
       <dependency>
         <groupId>org.assertj</groupId>
         <artifactId>assertj-core</artifactId>
-        <version>3.20.2</version>
+        <version>3.21.0</version>
         <scope>test</scope>
       </dependency>
     </dependencies>