Improve the testing task and workflow

[faboshka]

This PR adds a couple of improvements to the testing task and workflow:

• Separate test dependencies from the dev dependencies
  • This way there'd be less packages to install during the poetry install command in the testing workflow
  • This doesn't help the lint flow as we're usually linting the whole codebase including the tests
• Parallelize the tests running across all cores
  • This does improve the execution time a bit but the improvement is negligible as the whole test suite takes ~3 seconds to test
  • Adding this because it is cool 😃
• Change the test reporter used to a fork of dorney's test reporter
  • Replaced in order to allow for step-summary instead of an additional check (cleaner look)
• Add GitHub annotations to the failed tests using a plugin to be installed on the GitHub testing workflow run
• Have the summary be only a summary (without listing the issues and without annotations) as there is a different plugin for it now