Upgrade build tooling

[Miles-Garnsey]

The current gradle version (6.0.1) is two years old and the build is using deprecated features.

We should make an effort to upgrade the build tooling to gradle 7.0.

[albundy83]

And in short, if you can at least upgrade snakeyaml to 1.26, there is a CVE open on 1.23:

https://avd.aquasec.com/nvd/cve-2017-18640/