Refactor GH workflows

[zaro0508]

Refactor Github action from a single workflow to multiple workflows. The purpose is to make the workflows easier to follow and understand. Explanation of workflows..

• check: runs before a merge (i.e. PRs) or after a push (merge or forced push). Mainly for running quick validation jobs.
• gate: runs after a merge or a forced push to any branch. Allows admins to trigger long running integration tests as a gate to merging into the main branch.
• release: runs on a tag to publish Sceptre to registries and repositories

[tarkatronic]

Just a few comments and questions!

[zaro0508]

i've made quite a few changes to PR #1420 since your review @tarkatronic. let's get that merged first and i'll redo this PR. With the job dependencies setup in #1420 i'm still not sure it's possible or even worth it to split this setup into multiple workflows.

[zaro0508]

@tarkatronic i've redone this PR with updated files. could you please take another look?

[tarkatronic]

Looks great!

Fun fact for the future, it may be possible to do away with the PYPI_API_TOKEN secret, using PyPI's "Trusted Publishers" setup: https://docs.pypi.org/trusted-publishers/

[zaro0508]

Fun fact for the future, it may be possible to do away with the PYPI_API_TOKEN secret, using PyPI's "Trusted Publishers" setup: https://docs.pypi.org/trusted-publishers/

Yeah, i notice that. The problem with that setup is that it needs to be configure every time we create a new repo (think of sceptre plugin) in this org which means that it's another manual bootstrapping step. Tokens on the other hand can be shared at the org level so less manual setup.