Upgrade Freefair AspectJ plugin to v5.0.1
The `io.freefair.aspectj.post-compile-weaving` plugin v5.0.1 includes [a fix](https://github.com/freefair/gradle-plugins/pull/213) that allows all tasks for `./gradlew classes` to be marked as `UP-TO-DATE` following an initial `./gradlew clean classes`. Without this fix, any compile task that is enhanced by the `io.freefair.aspectj.post-compile-weaving` plugin will incorrectly have compilation outputs configured as a _task input_, resulting in the task being out of date following a `clean compile`.