./gradle assemble uploadArchive -PMAVEN_USERNAME=<your_username> -PMAVEN_PASSWORD=<your_encrypted_password>
Get an account on https://maven.siruplab.com/ and look for your encrypted password here.
If the build fails with an error like javax.net.ssl.SSLPeerUnverifiedException: peer not authenticated
, check that you're running a version of Java later than 1.8.0_101. Earlier versions do not support Let's Encrypt certs.