Update the SPDX ID of license

[Goooler]

Seems the current used The Apache Software License, Version 2.0 is outdated, and it can't be recognized by Maven Central.

See https://central.sonatype.com/artifact/org.apache.ant/ant/1.10.15

[paulk-asert]

I am not sure it is the text in that field that is the problem. I actually just don't see the licenses or license tags appear at all in the ant pom. Perhaps those need to be added to the file here:

https://github.com/apache/ant/blob/master/src/etc/poms/ant/pom.xml

The parent pom seems to show the current wording still:

Or maybe the semantics are that those fields should be "inherited" from the parent pom but that website doesn't do that.

[Goooler]

Seems license nodes are missing for all POM under https://github.com/apache/ant/tree/master/src/etc/poms, I'm not sure if we should append for them or not...

[bodewig]

I would expect the licenses to be inherited from https://github.com/apache/ant/blob/master/src/etc/poms/pom.xml

The license does show up with mvn help:effective-pom.