switch default build to gradle, fixes #47

[soloturn]

in case it does not work pls revert commit 7d256ad to switch the default back to mvn.

[soloturn]

the signing failed here, am not sure if it is just because its my user though. in the fork the following settings are there, and it signs the artefacts:

[arnaudroques]

But why is it failing in on build(8, ubuntu-20.04) only?
And the "create artifacts" step seems to be skipped in other jobs.
Any though?

[soloturn]

But why is it failing in on build(8, ubuntu-20.04) only? And the "create artifacts" step seems to be skipped in other jobs. Any though?

found it. maven has a condition in the pom.xml to sign only when the environment variable env.SIGN_ARTIFACTS is true. on a pull request this is not true, otherwise i could create a pull request and trigger signing with your key. which makes sense. for gradle, this condition was not there. it is now in the github workflow, in 2 steps. because it does not make a lot of sense in my opinion to call "gradle sign" AND set an environment variable to make it sign.