fix: migrates docker images to python:3.9-slim

[britton-from-notion]

Context

When following the instructions in the project README to docker compose up to get started, I experienced a few build and run issues. These appear to be related to the infamous compatibility inconsistencies with python projects and docker alpine images. I took a pass at remedying the issue by switching the images to python:3.9-slim and switching the docker compose to reference the root dockerfile, and this fixed the build and runtime issues getting started with Grove.

Changes

• Migrates docker images from alpine to python:3.9-slim due to build failures caused by wheels incompatibility in the alpine based images
• Updates docker compose to use main Dockerfile due to failing runs referencing a non-existent setup.py file
• Adds github actions step that validates the Docker image builds successfully

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[hcpadkins]

Great catch on these, thank you for raising this pull-request to resolve these issues, and for adding the Docker build to CI.

[britton-from-notion]

@hcpadkins just following up on this! Cool to merge?

[hcpadkins]

Hey @britton-from-notion,

Sorry for the delay! We've had a few people out over the past week, but this looks good, I'll get this merged now.