ci: Run unit tests in github actions runners

[mudler]

This card is about having a Github action workflow, called "Unit tests" running the unit tests that are currently defined in the code:

• https://github.com/masa-finance/masa-oracle/tree/test/pkg/tests
• https://github.com/masa-finance/masa-oracle/blob/test/pkg/oracle_node_test.go

Action items

• Create a Github action workflow pipeline named "Unit tests"
• Create a way to run such tests locally as well (for example, with a Makefile or equivalent), and use that to run the tests in the CI
• Make sure the pipeline gates PRs and the workflow runs on the main branch as well.

[mudler]

This is done already - workflow are running https://github.com/masa-finance/masa-oracle/actions/workflows/tests.yaml