Use same artifactId prefix as modules

Changing the artifactId would normally require a corresponding change of package. But in this case, the parent does not include any Java code, so we should be OK.

Raising as a PR just in case anyone has concerns

pom.xml

@@ -24,7 +24,7 @@
     <version>59</version>
   </parent>
 
-  <artifactId>commons-math-parent</artifactId>
+  <artifactId>commons-math4-parent</artifactId>
   <version>4.0-SNAPSHOT</version>
   <packaging>pom</packaging>
   <name>Apache Commons Math</name>