Use SPDX license name

[rodgavila]

Maven is not able to detect that the license being used by Konfetti is ISC. Per recommendation from Maven, the SPDX license name should be used (https://maven.apache.org/pom.html#Licenses)

Using an [SPDX identifier](https://spdx.org/licenses/) as the license name is recommended

The SPDX identifier of the ISC license is just ISC.