Travis CI: Drop Java 12 build (Java 13 is now Generally Available). Do not allow the Java 13 build to fail.
Travis CI: Drop Java 12 build (Java 13 is now Generally Available). Do not allow the Java 13 build to fail.

flowable/flowable-engine,dbmalkovsky/flowable-engine,dbmalkovsky/flowable-engine,paulstapleton/flowable-engine,paulstapleton/flowable-engine,flowable/flowable-engine,dbmalkovsky/flowable-engine,flowable/flowable-engine,flowable/flowable-engine,paulstapleton/flowable-engine,dbmalkovsky/flowable-engine,paulstapleton/flowable-engine