Improve CI setup

🌴 Context

In #13 (closed), we described several improvements on how the CI setup for this project could be improved.

This MR implements those improvements.

🔬 What does this MR do?

• Run test against multiple go versions.
• Enable more security scanners.
• Use https://github.com/gotestyourself/gotestsum for running tests so that test reports are created and will feed https://docs.gitlab.com/ee/ci/testing/unit_test_reports.html.