Require Maven 3.9.6 or newer (#208)

Author: basil

access-modifier-checker/pom.xml

@@ -11,7 +11,7 @@
   <name>Custom Access Modifier Checker</name>
 
   <properties>
-    <maven.version>3.8.1</maven.version>
+    <maven.version>3.9.6</maven.version>
     <maven-plugin-tools.version>3.15.0</maven-plugin-tools.version>
   </properties>