chore(main): release 0.8.4

[github-actions[bot]]

:robot: I have created a release beep boop

0.8.4 (2023-03-08)

Features

• Add Playground Demo (#82) (f519eaf)
• CLI: adds force-sink flag (#84) (cb7e697)
• HTTP Processing & Secrets Retrieval (#77) (f4e7329)
• object named groups (#78) (d5f687c)
• setkey support (#81) (5419f5e)

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[github-actions[bot]]

:robot: Release is at https://github.com/brexhq/substation/releases/tag/v0.8.4 :sunflower: