Allow building with Maven minimum version 3.8.8.

Author: wrandelshofer

README.md

@@ -371,7 +371,7 @@ on the same computer:
 
 This project requires **at least** the items below to build it from source:
 
-- Maven 3.9.8
+- Maven 3.9.9
 - OpenJDK SE 22
 
 This project contains optimised code for various JDK versions.

pom.xml

@@ -162,7 +162,7 @@
             <configuration>
               <rules>
                 <requireMavenVersion>
-                  <version>3.9.9</version>
+                  <version>3.8.8</version>
                 </requireMavenVersion>
               </rules>
               <fail>true</fail>