Update Maven version to 3.6.3 (#303)
Update Maven version to 3.6.3 (#303)

The current version (3.6.1) is no longer available from most of the
Apache mirrors, which causes errors with setup. This fixes the issue by
updating the version of Maven being used to the current - 3.6.3
fluo-io/zetten,astralway/muchos,fluo-io/zetten,fluo-io/fluo-deploy,fluo-io/fluo-deploy,astralway/muchos