fix: canteen/canteen-maven-plugin/pom.xml to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-ORGCODEHAUSPLEXUS-31521
- https://snyk.io/vuln/SNYK-JAVA-ORGCODEHAUSPLEXUS-461102

Author: snyk-bot

canteen/canteen-maven-plugin/pom.xml

@@ -24,7 +24,7 @@
         <dependency>
             <groupId>org.apache.maven</groupId>
             <artifactId>maven-core</artifactId>
-            <version>3.3.9</version>
+            <version>3.8.4</version>
         </dependency>
 
         <dependency>