Hi!
We are getting the same 403 Forbidden response, if we run liquibase from gradle.
After analyzing the http requests, we found out, that with User-Agent: Java/1.8.0_252 we get the 403 Forbidden response, without it, it works fine.
curl -A "Java/1.8.0_252" http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-3.5.xsd -> 403