Run unit tests again for all lessons and rewrite all to JUnit 5

Due to the migration to Spring Boot 2.4 the Vintage dependency was no longer included by default, resulting in skipping all unit tests.

webgoat-lessons/http-proxies/pom.xml

@@ -18,17 +18,8 @@
         <dependency>
             <groupId>org.springframework.security</groupId>
             <artifactId>spring-security-test</artifactId>
-            <version>4.1.3.RELEASE</version>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-            <version>${junit.version}</version>
-            <type>jar</type>
-            <scope>test</scope>
-        </dependency>
-
     </dependencies>
 
 </project>