Handle publishing after Bintray/JCenter close down

[jamesmudd]

It was recently announced Bintray/JCenter will close 1st May 2021.

https://jfrog.com/blog/into-the-sunset-bintray-jcenter-gocenter-and-chartcenter/?utm_source=mkto&utm_medium=email&utm_campaign=bintray-sunset&utm_content=global-02-2021

jHDF is currently published on bintray https://bintray.com/jamesmudd/jhdf/jhdf/ and the releases are typically pushed from there to Maven central.

Need to update the Gradle script to publish directly to maven central as part of this work publishing should be moved to GH actions.

[jamesmudd]

#257 partially resolves this it switches away from jcenter for jhdf dependencies and add support for direct publishing to Sonatype but it does not implement an Github action to automate publishing.

[jamesmudd]

There is now a GH Action https://github.com/jamesmudd/jhdf/actions/workflows/release.yml to automate releases this was used for the v0.6.3 release.