derby.log is created after upgrading 4.0.0

[jdaugherty]

Running bootRun or any database migraiton task now creates a derby.log file under the project root as of 4.0.0. This can be moved to a logs folder with System.setProperty('derby.stream.error.file', 'logs/derby-error.log'), but it seems like the derby dependency shouldn't be exposed by the plugin. The cause appears to be org.liquibase.ext:liquibase-hibernate5, which pulls in the dependency org.liquibase:liquibase-test-harness

[jdaugherty]

Adding the below exclude in build.gradle:

 api "org.grails.plugins:database-migration:4.0.0", {
     exclude group: "org.liquibase", module: "liquibase-test-harness"
 }

Works around this issue in the mean time.

[rainboyan]

I submit a PR here #275