RFC: 4.x releases

[totallyzen]

Context

Now that we've got a release pipeline back in action, there is lots we can do to make things nicer.

I am raising this issue in order for community to gather and talk about what should be fixed as priorities and what improvements we want to add.

Known Issues

We know there are several areas we want to improve:

• We want to thin out dependencies where possible - prefer giving a ready container but not be biased on how you should connect to the container. Example: postgres containers enforcing SqlAclhemy, as seen in #445
• We want to improve package typing so people have better developer experiences, as seen in #305 and the PRs it spawned so far
• Adding new containers, as there is demand for it #439, #441, #389, etc

[!NOTE] The list above is not conclusive, please comment on this issue and show your support!