feat: updated dockerfile, deps, guide & fix src

- fix logical error, better non 200 resp message in main.py
- updated dependencies
- major updates to contributing guide
- quicker prod builds with reduced docker layers
- adds dockerfile for development
- updates github action for unit-tests

action.yml

@@ -61,7 +61,7 @@ inputs:
 
 runs:
   using: "docker"
-  image: "Dockerfile"
+  image: "dockerfile"
 
 branding:
   icon: "info"